feat: deprecate litestar.contrib.pydantic

[cofin]

Description

This PR continues preparation for 3.0 by deprecating litestar.contrib.pydantic in favor of litestar.plugins.pydantic

Closes

[codecov]

Codecov Report

Attention: Patch coverage is 99.53917% with 2 lines in your changes missing coverage. Please review.

Project coverage is 98.41%. Comparing base (98933a3) to head (7a97008).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
litestar/_openapi/schema_generation/examples.py	50.00%	1 Missing ⚠️
litestar/plugins/pydantic/utils.py	99.44%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3852      +/-   ##
==========================================
- Coverage   98.44%   98.41%   -0.03%     
==========================================
  Files         333      339       +6     
  Lines       15346    15371      +25     
  Branches     1693     1694       +1     
==========================================
+ Hits        15107    15128      +21     
- Misses        110      114       +4     
  Partials      129      129              

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
1.9% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

Documentation preview will be available shortly at https://litestar-org.github.io/litestar-docs-preview/3852