MatchIfTrue lambdas used in decorator matchers in VisitorBasedCodemodCommand hit pickle errors on large codebase

In a subclass of `VisitorBasedCodemodCommand`, I have code that creates a `@matchers.visit` with a MatchIfTrue lambda that throws a lambda pickling error when the codemod is run on a sufficiently large codebase. Running it on a file at a time is fine, because the `multiprocessing` work doesn't kick in.

Probably it deserves a call out in the docs of `MatchIfTrue` to use named functions instead of lambdas. I'm not sure what other solutions are available.

The command in question:

```python
def func_def_has_request_param_matcher() -> m.FunctionDef:
return m.FunctionDef(
params=m.Parameters(
params=m.MatchIfTrue(
lambda params: any(p.name.value == "request" for p in params)
),
)
)

class ReproCommand(VisitorBasedCodemodCommand):
DESCRIPTION = (
"Do cool thing."
)

@staticmethod
def add_args(_arg_parser: argparse.ArgumentParser) -> None:
return

@m.visit(func_def_has_request_param_matcher())
def _mark_func_def_includes_request_param(self, node: cst.FunctionDef) -> None:
self.context.scratch["cool-scratch"] = node
```

The error in question

$ python -m libcst.tool codemod commands.repro.ReproCommand src
Calculating full-repo metadata...
Executing codemod...
Traceback (most recent call last):
File "/Users/jeff.hodges/.asdf/installs/python/3.8.13/lib/python3.8/runpy.py", line 194, in _run_module_as_main
return _run_code(code, main_globals, None,
File "/Users/jeff.hodges/.asdf/installs/python/3.8.13/lib/python3.8/runpy.py", line 87, in _run_code
exec(code, run_globals)
File "/Users/jeff.hodges/src/github.com/color/color/local/virtualenv3/lib/python3.8/site-packages/libcst/tool.py", line 839, in
main(os.environ.get("LIBCST_TOOL_COMMAND_NAME", "libcst.tool"), sys.argv[1:])
File "/Users/jeff.hodges/src/github.com/color/color/local/virtualenv3/lib/python3.8/site-packages/libcst/tool.py", line 834, in main
return lookup.get(args.action or None, _invalid_command)(proc_name, command_args)
File "/Users/jeff.hodges/src/github.com/color/color/local/virtualenv3/lib/python3.8/site-packages/libcst/tool.py", line 572, in _codemod_impl
result = parallel_exec_transform_with_prettyprint(
File "/Users/jeff.hodges/src/github.com/color/color/local/virtualenv3/lib/python3.8/site-packages/libcst/codemod/_cli.py", line 638, in parallel_exec_transform_with_prettyprint
for result in p.imap_unordered(
File "/Users/jeff.hodges/.asdf/installs/python/3.8.13/lib/python3.8/multiprocessing/pool.py", line 448, in
return (item for chunk in result for item in chunk)
File "/Users/jeff.hodges/.asdf/installs/python/3.8.13/lib/python3.8/multiprocessing/pool.py", line 868, in next
raise value
File "/Users/jeff.hodges/.asdf/installs/python/3.8.13/lib/python3.8/multiprocessing/pool.py", line 537, in _handle_tasks
put(task)
File "/Users/jeff.hodges/.asdf/installs/python/3.8.13/lib/python3.8/multiprocessing/connection.py", line 206, in send
self._send_bytes(_ForkingPickler.dumps(obj))
File "/Users/jeff.hodges/.asdf/installs/python/3.8.13/lib/python3.8/multiprocessing/reduction.py", line 51, in dumps
cls(buf, protocol).dump(obj)
AttributeError: Can't pickle local object 'func_def_has_request_param_matcher..'

Inlining the matcher creation gets a slightly different error

$ python -m libcst.tool codemod commands.repro.ReproCommand src
Calculating full-repo metadata...
Executing codemod...
Traceback (most recent call last):
File "/Users/jeff.hodges/.asdf/installs/python/3.8.13/lib/python3.8/runpy.py", line 194, in _run_module_as_main
return _run_code(code, main_globals, None,
File "/Users/jeff.hodges/.asdf/installs/python/3.8.13/lib/python3.8/runpy.py", line 87, in _run_code
exec(code, run_globals)
File "/Users/jeff.hodges/src/github.com/color/color/local/virtualenv3/lib/python3.8/site-packages/libcst/tool.py", line 839, in
main(os.environ.get("LIBCST_TOOL_COMMAND_NAME", "libcst.tool"), sys.argv[1:])
File "/Users/jeff.hodges/src/github.com/color/color/local/virtualenv3/lib/python3.8/site-packages/libcst/tool.py", line 834, in main
return lookup.get(args.action or None, _invalid_command)(proc_name, command_args)
File "/Users/jeff.hodges/src/github.com/color/color/local/virtualenv3/lib/python3.8/site-packages/libcst/tool.py", line 572, in _codemod_impl
result = parallel_exec_transform_with_prettyprint(
File "/Users/jeff.hodges/src/github.com/color/color/local/virtualenv3/lib/python3.8/site-packages/libcst/codemod/_cli.py", line 638, in parallel_exec_transform_with_prettyprint
for result in p.imap_unordered(
File "/Users/jeff.hodges/.asdf/installs/python/3.8.13/lib/python3.8/multiprocessing/pool.py", line 448, in
return (item for chunk in result for item in chunk)
File "/Users/jeff.hodges/.asdf/installs/python/3.8.13/lib/python3.8/multiprocessing/pool.py", line 868, in next
raise value
File "/Users/jeff.hodges/.asdf/installs/python/3.8.13/lib/python3.8/multiprocessing/pool.py", line 537, in _handle_tasks
put(task)
File "/Users/jeff.hodges/.asdf/installs/python/3.8.13/lib/python3.8/multiprocessing/connection.py", line 206, in send
self._send_bytes(_ForkingPickler.dumps(obj))
File "/Users/jeff.hodges/.asdf/installs/python/3.8.13/lib/python3.8/multiprocessing/reduction.py", line 51, in dumps
cls(buf, protocol).dump(obj)
_pickle.PicklingError: Can't pickle at 0x10205b1f0>: attribute lookup ReproCommand. on projects.codemods.pycodemods.commands.repro failed

(Tangentially, if there's a better way to do this "match if any Node in this Sequence matches this pattern", I'm down to be told what that is)