Add image_example.py, use foxglove-schemas-protobuf package

[jhurliman]

Public-Facing Changes

• [Python] New image_example.py for writing RawImage, CameraCalibration, and ImageAnnotation
• [Python] Use foxglove-schemas-protobuf package instead of in-repo proto/pb2 files

[jhurliman]

pipenv run black --check --diff --color mcap
Traceback (most recent call last):
  File "/home/runner/.local/share/virtualenvs/python--WAQ1xVa/bin/black", line 5, in <module>
    from black import patched_main
  File "src/black/__init__.py", line 45, in <module>
  File "/home/runner/.local/share/virtualenvs/python--WAQ1xVa/lib/python3.10/site-packages/black/files.py", line 34, in <module>
    import tomli as tomllib
ModuleNotFoundError: No module named 'tomli'
make: *** [Makefile:42: lint] Error 1

How did this happen

[jtbandes]

It looks like the tomli issue was fixed in psf/black#3447 Maybe we can upgrade black to avoid this?

[jhurliman]

@jtbandes this PR already upgrades black to the latest version. It turned out to be a setuptools issued, which was fixed by upgrading the pipenv version we use in CI.