Problems with editable installs and setuptools >=64

With Python 3.11.3, I installed Shiny in a venv for another project, with pip install -e ../py-shiny, but when I did this, the new project couldn't find the py.typed file.

I'm not 100% sure, but I believe that this is because setuptools >=64 uses a new mechanism instead of egg-link.
See:

• https://github.com/python/mypy/issues/13392#issuecomment-1212727421
• https://github.com/pypa/setuptools/issues/3518

Apparently one can also install with strict mode (https://setuptools.pypa.io/en/latest/userguide/development_mode.html#strict-editable-installs):

pip install -e ../py-shiny --config-settings editable_mode=strict

I tried this with py-shiny, and it resulted in the JS and CSS web assets not being available when running an app. So we'll probably want to fix it in that case.

What does work for now is to use compat mode:

pip install -e ../py-shiny --config-settings editable_mode=compat

Reproduce the editable install with Python 3.11.3 using pip install -e ../py-shiny, then compare the default and strict modes described in the issue. Verify that strict editable installs expose both py.typed and the JavaScript and CSS web assets when running an app; the issue does not name specific files or tests.