Add method getTagValue that generalizes getCategory

[sungshik]

This PR fixes:

• Generalize getCategory in ProductionAdapter to get any tag value #2072

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 49%. Comparing base (42cf801) to head (f9f4dd9).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...rascalmpl/values/parsetrees/ProductionAdapter.java	0%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##              main   #2082   +/-   ##
=======================================
  Coverage       49%     49%           
- Complexity    6318    6324    +6     
=======================================
  Files          664     664           
  Lines        59632   59633    +1     
  Branches      8648    8648           
=======================================
+ Hits         29496   29506   +10     
+ Misses       27922   27917    -5     
+ Partials      2214    2210    -4     

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