Deprecate withCoproductInstance name

[MateuszKubuszok]

TODO:

• withSealedSubtypeHandled and withEnumCaseHandled as a replacement for withCoproductInstance
• similarly for withCoproductInstancePartial
• deprecate withCoproductInstance and withCoproductInstancePartial
• update documentation
  • replace withCoproductInstance with withSealedSubtypeHandled
  • mention withEnumCaseHandled as alternative
  • explain difference between withSealedSubtypeHandled and .matching in path DSL
• use withEnumCaseHandled in tests

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 90.30%. Comparing base (b71778f) to head (c07e3f3).
Report is 1 commits behind head on master.

Files	Patch %	Lines
...etime/dsl/PartialTransformerDefinitionMacros.scala	0.00%	1 Missing ⚠️
...compiletime/dsl/PartialTransformerIntoMacros.scala	50.00%	1 Missing ⚠️
...etime/dsl/PartialTransformerDefinitionMacros.scala	75.00%	1 Missing ⚠️
.../compiletime/dsl/TransformerDefinitionMacros.scala	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #500      +/-   ##
==========================================
- Coverage   90.43%   90.30%   -0.13%     
==========================================
  Files         129      128       -1     
  Lines        5059     5064       +5     
  Branches      445      445              
==========================================
- Hits         4575     4573       -2     
- Misses        484      491       +7     

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