[LucaCappelletti94]

For an existing user-defined type mood, PostgreSQL permits SELECT mood 'happy', meaning the value 'happy' with type mood. The parser rejects it in projections, predicates, and function arguments.

This PR adds support for this typed-constant syntax for user-defined types.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.35%. Comparing base (d32825d) to head (029855b).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2689      +/-   ##
==========================================
+ Coverage   81.29%   81.35%   +0.05%     
==========================================
  Files          42       42              
  Lines       33950    34008      +58     
  Branches    33950    34008      +58     
==========================================
+ Hits        27601    27667      +66     
  Misses       2785     2785              
+ Partials     3564     3556       -8     

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