Abstract away a `FuncEnum` (will use it in `best_model_selector.ReductionCriterion` and `NodeInputConstructors`)

[lena-kashtelyan]

Summary: Add a base class for any "enums of callables" that will actually play well with storage and provide a consistent and safe way to implement such enums.

Differential Revision: D63914989

[facebook-github-bot]

This pull request was exported from Phabricator. Differential Revision: D63914989

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 92.59259% with 2 lines in your changes missing coverage. Please review.

Project coverage is 95.67%. Comparing base (f2d86de) to head (a10a07b).

Files with missing lines	Patch %	Lines
ax/utils/common/func_enum.py	84.61%	2 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2887      +/-   ##
==========================================
- Coverage   95.67%   95.67%   -0.01%     
==========================================
  Files         502      504       +2     
  Lines       49511    49538      +27     
==========================================
+ Hits        47369    47394      +25     
- Misses       2142     2144       +2     

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[facebook-github-bot]

This pull request was exported from Phabricator. Differential Revision: D63914989

[facebook-github-bot]

This pull request was exported from Phabricator. Differential Revision: D63914989

[facebook-github-bot]

This pull request was exported from Phabricator. Differential Revision: D63914989

[facebook-github-bot]

This pull request has been merged in facebook/Ax@afa9a1145024edd6e16b6fecce909c95137baccd.