Rewrite of the code with initial Scala 3 implementation, fixes #201

[MateuszKubuszok]

DONE:

• rewritten whole derivation code from Scala 2-macro-implementation-tied, mostly untyped and lacking significant naming to more platform-agnostic and typed utilities with better names
• provided platform-specific implementations for platform-agnostic interfaces in Scala 2 and in Scala 3
• wired Scala 3 DSL to Scala 3 macros
• removed old macros
• removed deprecated features
  • TransformerFs
  • enableUnsafeOption flag
  • tests and benchmarks for the above
• split Transformer into Transformer and Transformer.AutoDerived, to avoid
  1. potentially expanding macros in implicit lookup, because it was catching not only user-provided implicits
  2. checking that this implicit was created by autoderivation macro (which introduces unnecessary boxing and ignores configs)
  3. discarding obtained implicit when it was autoderived
  4. effectively wasting CPU work
• sorted code inside internal package into internal.runtime, internal.compiletime.dsl, internal.compiletime.derivation, etc
• improved error logging in a few places
• added the ability to display structured logs from macro expansion (.enableMacrosLogging)

TODO:

• Fix implementations for chimney-macro-commons for edge cases in Scala 3 #324 (the only actual blocker, requires help from VL, ETA unknown fixed in Fix genBCode crashes and paramsWithTypes failures #336)
• check if some issues would become low hanging fruits (optional, we can do it after the first Scala 3 release)
  • Enable .withField*** when writing to Java bean #110 - this should be fixed on new architecture but we need a test
  • Ability to not use auto-derivation #166 - since we split Transformer into Transformer and Transformer.AutoDerived we could also have 2 methods: one using autoderived and manually provided Transformers and one using only manually provided, and this task would be done
  • withFieldComputed is ignored when enableBeanSetters #175 - this should be fixed on new architecture but we need a test
  • Default values and type incompatibilites #200 - this should be fixed on new architecture but we need a test
  • Handling nested generics with [_] #204 - we might check what is the issue and fix it in chimney-macro-commons
  • Locally defined implicit transformers are ignored #207 - this should be fixed on new architecture but we need a test
  • Protobufs oneof mapping could be improved - Better protobuf oneof support #331
• task that could be done in this or the next release
  • Add tests and then official support for Scala 3 macros handling Scala 2.13 code and vice-versa #280 - can be done later
  • Document Chimney internals #302
• cleanup before release
  • hide methods __updateConfig and similar from users - Hide internal helpers from DSL API #334
  • simplyfy macros(?) (optional, since only we look at them, we can modify the code any time) - we can do it later
  • address failing tests on Scala 3 - some of them are(?) bugs in compiler and/or munit (workaround? report?) - disabled for now Fix Scala 3's error message format #345
  • fix symbol ownership on Scala 3 - it fails -Xcheck-macros OR Scala3.js - delegated to ticker Fix symbol ownership shown when we enable -Xcheck-macros on Scala 3 #346
  • enable linters on Scala 3 (-Xcheck-macros, -Xunused*) - Add linters to Scala 3 #337
• provide documentation for changes
  • breaking change removed deprecated features - Sphinx documentation for 0.8 #339
  • breaking change split of Transformer into Transformer and Transformer.AutoDerived, reasons for doing so - Sphinx documentation for 0.8 #339
  • breaking change fixing Default values and type incompatibilites #200 - default value will not be used if the right field do exist in source value, but conversion for it couldn't be derived - Sphinx documentation for 0.8 #339
  • partially fixing Enable .withField*** when writing to Java bean #110 and withFieldComputed is ignored when enableBeanSetters #175 by allowing usage of getters to point to setter fields (when pairing exists) - Sphinx documentation for 0.8 #339 (only need to be mentioned in release announcement)
  • Sphinx docs for .enableMacrosLogging - Sphinx documentation for 0.8 #339
  • Scaladocs for Scala 3 DSL - Documentation for Scala 3 DSL and formatter update #338
  • Scaladocs for .enableMacrosLogging linking to Sphinx - Sphinx documentation for 0.8 #339
• check benchmarks for performance regressions in generated code
• check if rewrite affected how long macros compile some feedbacks from users might be better than our own checks
• remove scala-3 from ci.yml and docs.yml