[updated #7009] Add a `*.pyi` file for auto-completion & hints.

[Daraan]

This is an updated version of the PRs #7009 + https://github.com/Minokori/carla/pull/1 from @Minokori who did the main and initial work and further corrections from me. As #7009 has not been maintained in the last months and Blyron mentioned that they might close it I choose now to make this PR as a combined and rebased version of the mentioned PRs.
Of course we should favor #7009 should it be updated and I hope everyone is fine with me opening this alternative PR, if not please close it again or leave a comment.

Description

To enable auto-completion and hints in code editors such as VScode, create a *.pyi file. This feature is compatible with python 3.9 and later versions.

Where has this been tested?

• Platform(s): Windows Desktop (not by me), Ubuntu 22.04
• Python version(s): 3.7, 3.9, 3.10 (also IDE version)
• Unreal Engine version(s): N/A

Possible Drawbacks

Some type checking features are only available in later Python versions (3.9+), but as this is a *.pyi stub file it depends on the IDE and not the runtime version.

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This change is