feat(litestar): add get_session to plugin

[cofin]

Adds the configuration get_session and provide_session methods to the SQLAlchemyPlugin for Litestar.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 30.00000% with 21 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.43%. Comparing base (f3c9309) to head (d83d4c6).

Files with missing lines	Patch %	Lines
...ed_alchemy/extensions/litestar/plugins/__init__.py	30.00%	21 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #461      +/-   ##
==========================================
- Coverage   78.67%   78.43%   -0.25%     
==========================================
  Files          86       86              
  Lines        6177     6205      +28     
  Branches      777      781       +4     
==========================================
+ Hits         4860     4867       +7     
- Misses       1068     1089      +21     
  Partials      249      249              

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[sonarqubecloud]

Quality Gate failed

Failed conditions
23.7% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube Cloud

[sonarqubecloud]

Quality Gate failed

Failed conditions
23.7% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube Cloud

[github-actions]

Documentation preview will be available shortly at https://litestar-org.github.io/advanced-alchemy-docs-preview/461