✅ Fixed filtering by producer/magazine on anime/manga search endpoints

[pushrbx]

Fixes #517
Currently if you search by producer or magazine on anime/manga search endpoints respectively together with other filter parameters, you won't get back any results because the database query for the search was constructed incorrectly.
This PR fixes that problem.

Additional changes:

• Improved model factories to increase the randomness of the generated models.
• Added the model factory state overrides for filters "score", "magazines" and "producers", so getOverridesFromQueryStringParameters method will manufacture the correct models when asked with these params.
• Added test for the use case described in 🐛 API Returns Empty Response When 'score' and 'producers' Parameters are Used Together #517

[codecov]

Codecov Report

Attention: Patch coverage is 52.63158% with 9 lines in your changes are missing coverage. Please review.

Project coverage is 57.76%. Comparing base (c425c32) to head (9342407).

Files	Patch %	Lines
app/Anime.php	50.00%	9 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #528      +/-   ##
============================================
+ Coverage     57.45%   57.76%   +0.30%     
  Complexity     1352     1352              
============================================
  Files           339      339              
  Lines          5209     5209              
============================================
+ Hits           2993     3009      +16     
+ Misses         2216     2200      -16     

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