Feature: support rectilinear chunk grid extension

[jhamman]

(Marking this as a draft for now)

closes: https://github.com/zarr-developers/zarr-python/issues/1595 replaces: https://github.com/zarr-developers/zarr-python/pull/1483 xref: https://github.com/zarr-developers/zarr-extensions/pull/25

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/user-guide/*.md
• [x] Changes documented as a new file in changes/
• [x] GitHub Actions have all passed
• [ ] Test coverage is 100% (Codecov passes)

[codecov[bot]]

Codecov Report

:x: Patch coverage is 75.31532% with 137 lines in your changes missing coverage. Please review. :white_check_mark: Project coverage is 62.18%. Comparing base (950066b) to head (6eab392). :warning: Report is 12 commits behind head on main.

Files with missing lines	Patch %	Lines
src/zarr/core/chunk_grids.py	67.24%	94 Missing :warning:
src/zarr/core/indexing.py	85.07%	20 Missing :warning:
src/zarr/testing/strategies.py	89.15%	9 Missing :warning:
src/zarr/core/array.py	81.39%	8 Missing :warning:
src/zarr/core/metadata/v3.py	25.00%	6 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3534      +/-   ##
==========================================
+ Coverage   61.86%   62.18%   +0.32%     
==========================================
  Files          85       85              
  Lines       10111    10604     +493     
==========================================
+ Hits         6255     6594     +339     
- Misses       3856     4010     +154     

Files with missing lines	Coverage Δ
src/zarr/api/synchronous.py	36.61% <ø> (ø)
src/zarr/core/group.py	70.27% <ø> (+0.03%)	:arrow_up:
src/zarr/core/metadata/v3.py	59.91% <25.00%> (+1.88%)	:arrow_up:
src/zarr/core/array.py	68.69% <81.39%> (+0.07%)	:arrow_up:
src/zarr/testing/strategies.py	94.11% <89.15%> (-3.70%)	:arrow_down:
src/zarr/core/indexing.py	70.19% <85.07%> (+0.73%)	:arrow_up:
src/zarr/core/chunk_grids.py	64.10% <67.24%> (+4.28%)	:arrow_up:

... and 7 files with indirect coverage changes

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