chore: support sqlalchemy 2.x and flask-sqlalchemy 3 (breaking)

[dpgaspar]

Description

• Added config option to not create FAB's tables FAB_CREATE_DB
• Flask-SQLAlchemy singleton is now created by FAB, import from flask_appbuilder.extensions import db. This means init now is simpler: appbuilder.init_app(app)
• appbuilder.sm.get_session was renamed to appbuilder.sm.session
• Doing queries now require an app_context (breaking from flask-sqlalchemy)
• SQLAInterface will not swallow exceptions, and accepts an optional parameter to commit or not commit
• appbuilder.get_app does not exist anymore, use current_app instead, you can still use appbuilder.app but it's deprecated

ADDITIONAL INFORMATION

• Has associated issue:
• Is CRUD MVC related.
• Is Auth, RBAC security related.
• Changes the security db schema.
• Introduces new feature
• Removes existing feature

[hasansezertasan]

Related: #2240

[ddorian]

Also related #2038 #2162 #2108 #1940

[codecov]

Codecov Report

Attention: Patch coverage is 85.53371% with 103 lines in your changes missing coverage. Please review.

Project coverage is 74.21%. Comparing base (c65e067) to head (68be010).
Report is 39 commits behind head on master.

Files with missing lines	Patch %	Lines
flask_appbuilder/security/sqla/manager.py	73.07%	28 Missing ⚠️
flask_appbuilder/models/sqla/interface.py	84.68%	17 Missing ⚠️
flask_appbuilder/models/sqla/base_legacy.py	72.72%	15 Missing ⚠️
flask_appbuilder/views.py	58.33%	10 Missing ⚠️
flask_appbuilder/api/__init__.py	91.17%	6 Missing ⚠️
flask_appbuilder/base.py	91.48%	4 Missing ⚠️
flask_appbuilder/security/manager.py	95.50%	4 Missing ⚠️
flask_appbuilder/utils/legacy.py	78.94%	4 Missing ⚠️
flask_appbuilder/cli.py	87.50%	3 Missing ⚠️
flask_appbuilder/models/sqla/base.py	78.57%	3 Missing ⚠️
... and 6 more

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2241      +/-   ##
==========================================
+ Coverage   73.81%   74.21%   +0.39%     
==========================================
  Files          72       76       +4     
  Lines        8754     9206     +452     
==========================================
+ Hits         6462     6832     +370     
- Misses       2292     2374      +82     

Flag	Coverage Δ
python	74.21% <85.53%> (+0.39%)	⬆️

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[ecederstrand]

Just noting here that this ends up limiting us to using older versions of Pandas because pandas.read_sql() now requires SQLAlchemy >= 2.0. We're using Pandas in Airflow DAGs, and apache-airlfow has a dependency on apache-airflow-providers-fab which again has a dependency on Flask-AppBuilder.

[potiuk]

Hey @dpgaspar - we are testing the alpha version of FAB 5 for Airlow and we think this one gives us a hard time running our tests.

Basically in our tests we are creating a number of FabAppBuilders (and we override some parts of it) - but we have an issue that when we access a session in pytest (and we run init_app multiple times in the same interpreter - in pytest - every time with a different App, the session that gets created here stays connected - we have > 90 connections to PostgresDB while running tests and we have very hard time on tracking where and how they should be closed.

Does it ring a bell?