Merge type stubs

[altendky]

Draft for:

• [ ] Continue enabling more mypy options...
• [ ] Fix existing complaints
• [ ] Compare against trio-typing
• [x] https://github.com/python/typeshed/pull/5013
• [ ] Review nitpick_ignores
• [ ] Remove type descriptions in docstrings
  • Need to check what the documentation setup does presently
• [ ] Organize type aliases
• [ ] Consider stubtest to help with verifying dynamic stuff
• [ ] Suggestions
  • [ ] Make CapacityLimiter generic https://github.com/python-trio/trio/pull/1873#discussion_r584281535
  • [ ] More specific .__aexit__() hints https://github.com/python-trio/trio/pull/1873#pullrequestreview-601634148

[codecov[bot]]

Codecov Report

Merging #1873 (9ecbc1d) into master (ff86c60) will decrease coverage by 0.37%. The diff coverage is 96.92%.

@@            Coverage Diff             @@
##           master    #1873      +/-   ##
==========================================
- Coverage   99.59%   99.21%   -0.38%     
==========================================
  Files         114      115       +1     
  Lines       14574    14914     +340     
  Branches     1110     1115       +5     
==========================================
+ Hits        14515    14797     +282     
- Misses         42       96      +54     
- Partials       17       21       +4     

Impacted Files	Coverage Δ
trio/_subprocess_platform/waitid.py	66.66% <50.00%> (-2.57%)	:arrow_down:
trio/_file_io.py	73.94% <63.72%> (-26.06%)	:arrow_down:
trio/_tools/gen_exports.py	94.50% <70.58%> (-5.50%)	:arrow_down:
trio/_typing.py	85.71% <85.71%> (ø)
trio/_highlevel_open_unix_stream.py	89.65% <87.50%> (-1.65%)	:arrow_down:
trio/_highlevel_socket.py	98.30% <89.47%> (-1.70%)	:arrow_down:
trio/_core/_io_kqueue.py	85.82% <90.47%> (+0.34%)	:arrow_up:
trio/_core/_local.py	97.05% <93.33%> (-2.95%)	:arrow_down:
trio/tests/test_subprocess.py	98.67% <93.44%> (-1.33%)	:arrow_down:
trio/_core/_multierror.py	98.93% <94.28%> (-1.07%)	:arrow_down:
... and 89 more

[Zac-HD]

Closing this as stale; it looks like we're taking a more incremental approach - so far in #2477, #2671, #2682, and generally with https://github.com/python-trio/trio/pulls?q=is%3Apr+label%3Atyping. I really appreciate all the work that went into this though!