Add typing to most Array properties

[dstansby]

This adds returns typing to most properties of Array.

TODO:

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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.99%. Comparing base (6105ef2) to head (ba56199).

❗ Current head ba56199 differs from pull request most recent head af0d5fa. Consider uploading reports for the commit af0d5fa to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1711   +/-   ##
=======================================
  Coverage   99.98%   99.99%           
=======================================
  Files          38       38           
  Lines       14640    14571   -69     
=======================================
- Hits        14638    14570   -68     
+ Misses          2        1    -1     

Files	Coverage Δ
zarr/core.py	100.00% <100.00%> (ø)

... and 6 files with indirect coverage changes