Make raw serializers more lenient

[Lipen]

This PR makes the serializers for EtsRawStmt, EtsRawValue, EtsRawType more lenient, i.e., allow them accept JSONs that use kind discriminator instead of _.

[codecov]

Codecov Report

❌ Patch coverage is 45.16129% with 17 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.74%. Comparing base (da338ff) to head (3aa75b8).
⚠️ Report is 5 commits behind head on neo.

Files with missing lines	Patch %	Lines
.../src/main/kotlin/org/jacodb/ets/dto/Serializers.kt	45.16%	14 Missing and 3 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                neo     #330      +/-   ##
============================================
- Coverage     70.19%   69.74%   -0.45%     
+ Complexity     2493     2491       -2     
============================================
  Files           275      275              
  Lines         15462    15573     +111     
  Branches       2307     2345      +38     
============================================
+ Hits          10853    10862       +9     
- Misses         3689     3782      +93     
- Partials        920      929       +9     

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[github-actions]

Test Results

  215 files  ±0    215 suites  ±0   15m 48s ⏱️ -23s
  711 tests ±0    699 ✅  -  7  12 💤 + 7  0 ❌ ±0 
1 977 runs  ±0  1 927 ✅  - 21  50 💤 +21  0 ❌ ±0 

Results for commit 3aa75b8. ± Comparison against base commit da338ff.

♻️ This comment has been updated with latest results.