Include cirq.contrib test JSON files in cirq-core package

[pavoljuhas]

Note the package name temporarily uses f-string to avoid triggering
the check/misc check. To be cleaned up with explicit allow-patterns
in check/misc later.

[pavoljuhas]

Follow up to #7396

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.53%. Comparing base (bbbf952) to head (5f2eb88).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7529      +/-   ##
==========================================
- Coverage   97.53%   97.53%   -0.01%     
==========================================
  Files        1095     1095              
  Lines       99016    99016              
==========================================
- Hits        96580    96579       -1     
- Misses       2436     2437       +1     

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