Add support for Flask-SQLAlchemy-Lite datastore

[jwag956]

• This introduces new pre-configured models that use 'modern' sqlalchemy type annotations
• The querying is done using the 2.0 select() mechanism (rather than the old query interface)
• Enhance view_scaffold test harness to work with either Flask-SQLAlchemy or Flask-SQLAlchemy-Lite
• FS-Lite requires newer Flask/Werkzeug - bump up lowest tested versions
• per sqlalchemy best practice - don't install mypy extension or stubs

close #989

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.49%. Comparing base (ec70c1d) to head (5f07f1c).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #994      +/-   ##
==========================================
+ Coverage   98.45%   98.49%   +0.03%     
==========================================
  Files          36       37       +1     
  Lines        4665     4777     +112     
==========================================
+ Hits         4593     4705     +112     
  Misses         72       72              

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