Fix order handling

[dstansby]

This is many fixes to how 'order' is handled. See the changelong entries for details of bugs fixed.

Fixes #2948, and helps with #3072.

[codecov]

Codecov Report

Attention: Patch coverage is 90.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 59.57%. Comparing base (7a162bf) to head (6a55eae).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/zarr/api/asynchronous.py	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3112      +/-   ##
==========================================
- Coverage   59.58%   59.57%   -0.01%     
==========================================
  Files          78       78              
  Lines        8694     8686       -8     
==========================================
- Hits         5180     5175       -5     
+ Misses       3514     3511       -3     

Files with missing lines	Coverage Δ
src/zarr/core/array.py	69.02% <100.00%> (ø)
src/zarr/core/group.py	69.33% <ø> (ø)
src/zarr/api/asynchronous.py	70.27% <66.66%> (+0.20%)	⬆️

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[d-v-b]

this looks good other than the text of the warning that claims that zarr v3 arrays are always stored in C order. That text needs to be made more precise.