Add is_wrapped utility function for Fabric

[Atharva-Phatak]

What does this PR do?

Method to check whether a Fabric model was set up already #16484

Fixes #16484

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[codecov]

Codecov Report

Merging #16953 (576a5e3) into master (a8c4d1f) will decrease coverage by 23%.
The diff coverage is 100%.

Additional details and impacted files

@@            Coverage Diff            @@
##           master   #16953     +/-   ##
=========================================
- Coverage      82%      59%    -23%     
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  Files         438      413     -25     
  Lines       31756    31459    -297     
=========================================
- Hits        25994    18660   -7334     
- Misses       5762    12799   +7037     

[justusschock]

Looks good already. Added a few comments.
Don't forget to add a changelog entry :)