[python] Error if extending enum past index type limit

[nguyenv]

Issue and/or context:

#1975

Changes:

Raise ValueError if the number of enumerations exceeds the limit of the index value type.

[johnkerl]

LGTM although I'd love to get @bkmartinjr 's eyes on it as well

[bkmartinjr]

looks right to me.

[codecov]

Codecov Report

Merging #1986 (a93df73) into main (d712bf2) will increase coverage by 35.78%.
The diff coverage is 100.00%.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1986       +/-   ##
===========================================
+ Coverage   53.97%   89.75%   +35.78%     
===========================================
  Files         112       34       -78     
  Lines        8780     3603     -5177     
  Branches      161        0      -161     
===========================================
- Hits         4739     3234     -1505     
+ Misses       3966      369     -3597     
+ Partials       75        0       -75     

Flag	Coverage Δ
libtiledbsoma	?
python	89.75% <100.00%> (?)
r	?

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Components	Coverage Δ
python_api	89.75% <100.00%> (∅)
libtiledbsoma	∅ <ø> (∅)