Enable checking of untyped definitions

[dstansby]

This enables some more mypy checks. The first two didn't need any fixes. check_untyped_defs requires quite a lot of fixes. I've made some of them, and added a list of modules that need a lot of fixes to ignore for now. The idea here is that at least in any other newly added modules untyped definitions will be checked.

TODO:

• [x] Add unit tests and/or doctests in docstrings
• [x] Add docstrings and API docs for any new/modified user-facing classes and functions
• [x] New/modified features documented in docs/tutorial.rst
• [x] Changes documented in docs/release.rst
• [x] GitHub Actions have all passed
• [x] Test coverage is 100% (Codecov passes)

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 99.99%. Comparing base (6105ef2) to head (80293c5).

:exclamation: Current head 80293c5 differs from pull request most recent head cd5ed41. Consider uploading reports for the commit cd5ed41 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1612   +/-   ##
=======================================
  Coverage   99.98%   99.99%           
=======================================
  Files          38       38           
  Lines       14640    14575   -65     
=======================================
- Hits        14638    14574   -64     
+ Misses          2        1    -1     

Files	Coverage Δ
zarr/_storage/v3.py	100.00% <100.00%> (ø)
zarr/attrs.py	100.00% <100.00%> (ø)
zarr/core.py	100.00% <100.00%> (ø)
zarr/hierarchy.py	100.00% <100.00%> (+0.20%)	:arrow_up:
zarr/indexing.py	100.00% <100.00%> (ø)
zarr/n5.py	100.00% <100.00%> (ø)
zarr/storage.py	100.00% <100.00%> (ø)
zarr/sync.py	100.00% <100.00%> (ø)
zarr/util.py	100.00% <ø> (ø)

... and 2 files with indirect coverage changes

[dstansby]

Anything more to do here before this can be merged?

[dstansby]

I'll close this since it's gone in to the v3 branch