feat: deprecate litestar.contrib.sqlalchemy

[cofin]

Description

This PR deprecates the litestar.contrib.sqlalchemy module in favor of litestar.plugins.sqlalchemy

Closes

[codecov]

Codecov Report

Attention: Patch coverage is 99.05660% with 2 lines in your changes missing coverage. Please review.

Project coverage is 98.35%. Comparing base (8e875c1) to head (97ee362).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
litestar/contrib/sqlalchemy/__init__.py	93.75%	0 Missing and 1 partial ⚠️
litestar/contrib/sqlalchemy/repository/__init__.py	92.85%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##             main    #3755    +/-   ##
========================================
  Coverage   98.35%   98.35%            
========================================
  Files         331      332     +1     
  Lines       15287    15460   +173     
  Branches     2447     2460    +13     
========================================
+ Hits        15035    15206   +171     
  Misses        112      112            
- Partials      140      142     +2     

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[github-actions]

Documentation preview will be available shortly at https://litestar-org.github.io/litestar-docs-preview/3755