feat(#536): add support .csv files for open_fixture

[HairlessVillager]

Description

Add comprehensive CSV file support to the open_fixture and open_fixture_async functions, expanding the fixture loading capabilities beyond JSON to include comma-separated value files.

Closes

Closes #536

[codecov-commenter]

Codecov Report

❌ Patch coverage is 66.23377% with 26 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.05%. Comparing base (8916358) to head (a084059).

Files with missing lines	Patch %	Lines
advanced_alchemy/utils/fixtures.py	66.23%	24 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #615      +/-   ##
==========================================
- Coverage   79.09%   79.05%   -0.05%     
==========================================
  Files          99       99              
  Lines        7861     7915      +54     
  Branches     1065     1073       +8     
==========================================
+ Hits         6218     6257      +39     
- Misses       1301     1315      +14     
- Partials      342      343       +1     

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[github-actions]

Documentation preview will be available shortly at https://litestar-org.github.io/advanced-alchemy-docs-preview/615

[cofin]

@HairlessVillager do you mind if i make a few tweaks to this before we merge? Overall, it's not bad but there are few improvements to add.

For instance, I think I don't think we can use splitlines here because you could have a CSV with a line feed within quotation marks of a cell. There are also a few async updates to introduce.

Sorry for the long time between you creating this and my review.

[HairlessVillager]

@HairlessVillager do you mind if i make a few tweaks to this before we merge? Overall, it's not bad but there are few improvements to add.

For instance, I think I don't think we can use splitlines here because you could have a CSV with a line feed within quotation marks of a cell. There are also a few async updates to introduce.

Sorry for the long time between you creating this and my review.

Please go ahead with the tweaks, I appreciate you taking the time to review it!