[r] Call array schema evolution after loop setting up enums

[eddelbuettel]

Issue and/or context:

See #2197 for context and the Python example: multiple calls to evolve an array schema can have side effects.

Changes:

On write, one call is now made (as needed) which is similar to what the update process already did.

Notes for Reviewer:

SC 42531

[shortcut-integration]

This pull request has been linked to Shortcut Story #42531: [r] Fix race in SOMADataFrame schema with multiple enumerated columns.

[codecov]

Codecov Report

Merging #2201 (5036c46) into main (9134e2c) will decrease coverage by 3.85%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2201      +/-   ##
==========================================
- Coverage   78.54%   74.69%   -3.85%     
==========================================
  Files         137       52      -85     
  Lines       10681     4347    -6334     
  Branches      215        0     -215     
==========================================
- Hits         8389     3247    -5142     
+ Misses       2194     1100    -1094     
+ Partials       98        0      -98     

Flag	Coverage Δ
libtiledbsoma	?
python	?
r	74.69% <100.00%> (+0.01%)	⬆️

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Components	Coverage Δ
python_api	∅ <ø> (∅)
libtiledbsoma	∅ <ø> (∅)