Add stubs to python bindings to provide typing information.

[0mdc]

Motivation and Context

This changeset adds stubs to python bindings to provide typing information. Stub generation depends on pybind11-stubgen.

https://github.com/facebookresearch/habitat-sim/assets/110583667/86593700-7896-4dc5-9ca7-a6d077beaad9

How to test:

• pip install pybind11-stubgen.
• Build habitat-sim normally.
• Import the package in another project, and explore types in your IDE.

WIP:

• Stubs contain some errors, but they mostly work.
• CI is not yet handled.
• Ideally, creating a stub package would scale better, but I could not make it work with bindings. See PEP 561.

How Has This Been Tested

Tested by importing habitat_sim in an external Python file.

Types of changes

• [x] New feature (non-breaking change which adds functionality)

Checklist

• [x] My code follows the code style of this project.
• [x] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [x] I have completed my CLA (see CONTRIBUTING)
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.