Add check/handle gracefully attempt to upload/rename asset to have path longer than 512 characters

512 is current length limit for the path, and it is more than enough. (the longest path in archive I found is 192:

dandi@drogon:/mnt/backup/dandi/dandisets$ declare m=0;for ds in 00*; do git -C $ds ls-tree -r --name-only HEAD; done | awk '{ if (length($0) > max) max = length($0) } END { print max }'
192
dandi@drogon:/mnt/backup/dandi/dandisets$ pwd
/mnt/backup/dandi/dandisets

but if I do attempt to upload a file with path length greater -- it causes 500

❯ DANDI_DEVEL=1 dandi upload --allow-any-path $fn
2024-03-06 20:34:17,039 [    INFO] Found 2 files to consider
PATH                              SIZE    ERRORS PROGRESS STATUS          MESSAGE        
dandiset.yaml                     3.0 kB                  skipped         should be ed...
...901234567890123456789_data.dat 4 Bytes   0             producing asset                
Summary:                          3.1 kB                  1 skipped       1 should be ...
                                                          1 producing ...                
...901234567890123456789_data.dat 4 Bytes   0             ERROR           500 Server E...
Summary:                          3.1 kB                  1 skipped       1 should be ...
                                                          1 ERROR         1 500 Server...
2024-03-06 20:35:13,412 [    INFO] Logs saved in /home/yoh/.local/state/dandi-cli/log/20240307013414Z-313889.log
Traceback (most recent call last):
  File "/home/yoh/proj/dandi/dandi-cli-master/venvs/dev3.11/bin/dandi", line 8, in <module>
    sys.exit(main())
             ^^^^^^
  File "/home/yoh/proj/dandi/dandi-cli-master/venvs/dev3.11/lib/python3.11/site-packages/click/core.py", line 1157, in __call__
    return self.main(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/yoh/proj/dandi/dandi-cli-master/venvs/dev3.11/lib/python3.11/site-packages/click/core.py", line 1078, in main
    rv = self.invoke(ctx)
         ^^^^^^^^^^^^^^^^
  File "/home/yoh/proj/dandi/dandi-cli-master/venvs/dev3.11/lib/python3.11/site-packages/click/core.py", line 1688, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/yoh/proj/dandi/dandi-cli-master/venvs/dev3.11/lib/python3.11/site-packages/click/core.py", line 1434, in invoke
    return ctx.invoke(self.callback, **ctx.params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/yoh/proj/dandi/dandi-cli-master/venvs/dev3.11/lib/python3.11/site-packages/click/core.py", line 783, in invoke
    return __callback(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/yoh/proj/dandi/dandi-cli-master/venvs/dev3.11/lib/python3.11/site-packages/click/decorators.py", line 45, in new_func
    return f(get_current_context().obj, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/yoh/proj/dandi/dandi-cli-master/dandi/cli/base.py", line 126, in wrapper
    return f(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^
  File "/home/yoh/proj/dandi/dandi-cli-master/dandi/cli/cmd_upload.py", line 103, in upload
    upload(
  File "/home/yoh/proj/dandi/dandi-cli-master/dandi/upload.py", line 459, in upload
    raise upload_err
  File "/home/yoh/proj/dandi/dandi-cli-master/dandi/upload.py", line 357, in process_path
    for r in dfile.iter_upload(
  File "/home/yoh/proj/dandi/dandi-cli-master/dandi/files/bases.py", line 455, in iter_upload
    r = client.post(
        ^^^^^^^^^^^^
  File "/home/yoh/proj/dandi/dandi-cli-master/dandi/dandiapi.py", line 306, in post
    return self.request("POST", path, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/yoh/proj/dandi/dandi-cli-master/dandi/dandiapi.py", line 200, in request
    for i, attempt in enumerate(
  File "/home/yoh/proj/dandi/dandi-cli-master/venvs/dev3.11/lib/python3.11/site-packages/tenacity/__init__.py", line 347, in __iter__
    do = self.iter(retry_state=retry_state)
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/yoh/proj/dandi/dandi-cli-master/venvs/dev3.11/lib/python3.11/site-packages/tenacity/__init__.py", line 325, in iter
    raise retry_exc.reraise()
          ^^^^^^^^^^^^^^^^^^^
  File "/home/yoh/proj/dandi/dandi-cli-master/venvs/dev3.11/lib/python3.11/site-packages/tenacity/__init__.py", line 158, in reraise
    raise self.last_attempt.result()
          ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/concurrent/futures/_base.py", line 449, in result
    return self.__get_result()
           ^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/concurrent/futures/_base.py", line 401, in __get_result
    raise self._exception
  File "/home/yoh/proj/dandi/dandi-cli-master/dandi/dandiapi.py", line 236, in request
    result.raise_for_status()
  File "/home/yoh/proj/dandi/dandi-cli-master/venvs/dev3.11/lib/python3.11/site-packages/requests/models.py", line 1021, in raise_for_status
    raise HTTPError(http_error_msg, response=self)
requests.exceptions.HTTPError: 500 Server Error: Internal Server Error for url: https://api.dandiarchive.org/api/dandisets/000029/versions/draft/assets/
DANDI_DEVEL=1 dandi upload --allow-any-path $fn  2.27s user 2.93s system 8% cpu 58.988 total
❯ 
❯ echo $fn
sub-123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789/sub-123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789_ses-1/sub-123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789_data.dat
❯ echo ${#fn}
596

and as we on 500 re-try -- poor dandi-archive keeps 500ing:

2024-03-07T01:40:14.785006+00:00 app[web.1]: 10.1.61.154 - - [07/Mar/2024:01:40:14 +0000] "POST /api/dandisets/000029/versions/draft/assets/ HTTP/1.1" 500 145 "-" "dandi/0.60.0+11.gee18a15e requests/2.31.0 CPython/3.11.8"
2024-03-07T01:40:14.785346+00:00 heroku[router]: at=info method=POST path="/api/dandisets/000029/versions/draft/assets/" host=api.dandiarchive.org request_id=4a509b4c-8716-4350-973c-33deaa1761f1 fwd="73.218.136.210" dyno=web.1 connect=0ms service=48ms status=500 bytes=512 protocol=https
2024-03-07T01:40:16.133195+00:00 heroku[router]: at=info method=POST path="/api/dandisets/000029/versions/draft/assets/" host=api.dandiarchive.org request_id=812d665f-2909-42de-88f3-8c400639f8fc fwd="73.218.136.210" dyno=web.1 connect=0ms service=47ms status=500 bytes=512 protocol=https
2024-03-07T01:40:16.132901+00:00 app[web.1]: 10.1.61.154 - - [07/Mar/2024:01:40:16 +0000] "POST /api/dandisets/000029/versions/draft/assets/ HTTP/1.1" 500 145 "-" "dandi/0.60.0+11.gee18a15e requests/2.31.0 CPython/3.11.8"
2024-03-07T01:40:17.783794+00:00 app[web.1]: 10.1.61.154 - - [07/Mar/2024:01:40:17 +0000] "POST /api/dandisets/000029/versions/draft/assets/ HTTP/1.1" 500 145 "-" "dandi/0.60.0+11.gee18a15e requests/2.31.0 CPython/3.11.8"
2024-03-07T01:40:17.783956+00:00 heroku[router]: at=info method=POST path="/api/dandisets/000029/versions/draft/assets/" host=api.dandiarchive.org request_id=f4646ed1-bd1e-4967-b18e-3a267cf8b4e3 fwd="73.218.136.210" dyno=web.1 connect=0ms service=38ms status=500 bytes=512 protocol=https
2024-03-07T01:40:19.934664+00:00 heroku[router]: at=info method=POST path="/api/dandisets/000029/versions/draft/assets/" host=api.dandiarchive.org request_id=bf87983c-40ba-41d9-ad2e-7ea1e5c53730 fwd="73.218.136.210" dyno=web.1 connect=0ms service=153ms status=500 bytes=512 protocol=https
2024-03-07T01:40:19.934340+00:00 app[web.1]: 10.1.61.154 - - [07/Mar/2024:01:40:19 +0000] "POST /api/dandisets/000029/versions/draft/assets/ HTTP/1.1" 500 145 "-" "dandi/0.60.0+11.gee18a15e requests/2.31.0 CPython/3.11.8"
2024-03-07T01:40:22.552730+00:00 app[web.1]: 10.1.61.154 - - [07/Mar/2024:01:40:22 +0000] "POST /api/dandisets/000029/versions/draft/assets/ HTTP/1.1" 500 145 "-" "dandi/0.60.0+11.gee18a15e requests/2.31.0 CPython/3.11.8"
2024-03-07T01:40:22.552988+00:00 heroku[router]: at=info method=POST path="/api/dandisets/000029/versions/draft/assets/" host=api.dandiarchive.org request_id=bf4b5372-c419-4939-aed2-682773abd707 fwd="73.218.136.210" dyno=web.1 connect=0ms service=48ms status=500 bytes=512 protocol=https
2024-03-07T01:40:25.712900+00:00 app[web.1]: 10.1.61.154 - - [07/Mar/2024:01:40:25 +0000] "POST /api/dandisets/000029/versions/draft/assets/ HTTP/1.1" 500 145 "-" "dandi/0.60.0+11.gee18a15e requests/2.31.0 CPython/3.11.8"
2024-03-07T01:40:25.713061+00:00 heroku[router]: at=info method=POST path="/api/dandisets/000029/versions/draft/assets/" host=api.dandiarchive.org request_id=690a9bbf-d31d-41f5-9d09-38335a3620de fwd="73.218.136.210" dyno=web.1 connect=0ms service=62ms status=500 bytes=512 protocol=https

I guess should be some kind of 400 code

Start at the API POST /api/dandisets/{id}/versions/draft/assets/ endpoint and trace how an asset path is validated. Reproduce the 596-character upload from the issue, then verify that an over-limit path returns a client error instead of 500 responses and repeated retries; the client-side call sites are dandi/upload.py and dandi/files/bases.py.