Continuing work towards #8988.
The first five commits were created using stubdefaulter on various Python versions; the following commits were all created manually by me to fix various problems. The main things this adds that weren't present in #9501 are:
- Defaults in Windows-only modules and Windows-only branches (because I'm running a Windows machine)
- Defaults in non-py311 branches
- Defaults for float parameters
- Defaults for overloads
The precise return type depends on the platform. Link to implementation:
68fb03249f/Lib/multiprocessing/connection.py (L518)
Now users no longer need to use the internal-looking class
`_ConnectionBase` in annotations, at least in code that doesn't
need to be cross-platform.
* Use `ClassVar` where applicable
* Fix `_Popen()` return types
* Remove non-existing field `BaseContext.Process`
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
