Use 'modern' query for all sqlalchemy datastores

[jwag956]

Stop using the model.query and convert to select(xx).where(yy) as recommended in sqlalchemy 2. All 3 sqlalchemy based datastores now share a common implementation.

the sqlalchemy_session datastore tests now use the new sqla models.

Update docs to note that using FsModels.sqla requires pythin 3.10 or higher.

To simplify code - the find_user() method now takes a single kwarg (attribute:value) for selecting - that is all FS ever used so supporting multiple added complexity.

Added a new low-level way to capture queries during unit tests - converted all tests to use that.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.40%. Comparing base (5744f9d) to head (361dec8).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1007      +/-   ##
==========================================
- Coverage   98.49%   98.40%   -0.10%     
==========================================
  Files          37       37              
  Lines        4783     4755      -28     
==========================================
- Hits         4711     4679      -32     
- Misses         72       76       +4     

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