Support CASESENSITIVE for TAG fields

[Avital-Fine]

Pull Request check-list

Please make sure to review and check all of these items:

• Does $ tox pass with this change (including linting)?
• Do the CI tests pass with this change (enable it first in your forked repo and wait for the github action build to finish)?
• Is the new or changed code fully tested?
• Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?
• Is there an example added to the examples folder (if applicable)?
• Was the change added to CHANGES file?

Closes #2040

[codecov-commenter]

Codecov Report

Merging #2112 (a3d2f07) into master (e5e265d) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2112      +/-   ##
==========================================
- Coverage   92.44%   92.43%   -0.02%     
==========================================
  Files         104      104              
  Lines       24364    24383      +19     
==========================================
+ Hits        22524    22538      +14     
- Misses       1840     1845       +5     

Impacted Files	Coverage Δ
redis/commands/search/field.py	98.57% <100.00%> (+0.08%)	⬆️
tests/test_search.py	99.19% <100.00%> (+0.01%)	⬆️
tests/test_cluster.py	97.36% <0.00%> (-0.24%)	⬇️
redis/asyncio/connection.py	84.49% <0.00%> (-0.12%)	⬇️
tests/test_graph.py	90.59% <0.00%> (-0.04%)	⬇️

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[chayim]

@Avital-Fine Any idea why under python 3.9 (hiredis) and only there - we see a unit test failure with the assert?