`multiprocessing` is missing several files

[sobolevn]

Directory in CPython: https://github.com/python/cpython/tree/main/Lib/multiprocessing
Directory in typeshed: https://github.com/python/typeshed/tree/master/stdlib/multiprocessing

• https://github.com/python/cpython/blob/main/Lib/multiprocessing/forkserver.py
• https://github.com/python/cpython/blob/main/Lib/multiprocessing/heap.py
• https://github.com/python/cpython/blob/main/Lib/multiprocessing/popen_fork.py
• https://github.com/python/cpython/blob/main/Lib/multiprocessing/popen_forkserver.py
• https://github.com/python/cpython/blob/main/Lib/multiprocessing/popen_spawn_posix.py
• https://github.com/python/cpython/blob/main/Lib/multiprocessing/popen_spawn_win32.py
• https://github.com/python/cpython/blob/main/Lib/multiprocessing/reduction.py
• https://github.com/python/cpython/blob/main/Lib/multiprocessing/resource_sharer.py
• https://github.com/python/cpython/blob/main/Lib/multiprocessing/resource_tracker.py
• https://github.com/python/cpython/blob/main/Lib/multiprocessing/util.py

[hauntsaninja]

Yup. All of these are undocumented, so relatively low pri (as per slightly outdated checklist in #4545 , issue also contains a script to get list of missing modules in stdlib).

[kkirsche]

Once the open merge requests are completed, I'll move onto the next series of files. I'm trying to avoid creating too many merge requests at any one time.

I seem to have missed where the script was in the linked issue to locate files/modules without stubs, but I'd be happy to address other modules if I can identify how to locate those.

[kkirsche]

Moving onto last two hopefully today, depending on my meeting schedule. If all goes to plan this should be able to be closed by the end of the week

[kkirsche]

This will be fixed when the remaining PR's are completed.

Note though that there are some additional opportunities in multiprocessing to expand stubs further, if interested