Migrate to scala 3

[ghostbuster91]

This fixes #257 , #265

TODO:

• [x] cross compile against scala3
• [x] migrate base type classes
• [x] migrate base tests
• [x] migrate ignore and modify macros
• [x] migrate useMatcher macro (https://github.com/softwaremill/diffx/blob/scala-3_0_2/core/src/main/scala-2/com/softwaremill/diffx/ModifyMacro.scala#L128)
• [x] fix auto-derivation (https://github.com/softwaremill/magnolia/issues/336) (Fixed in upstream by switch to invariant)
• [x] fix recursive coproducts derivation (https://github.com/softwaremill/diffx/blob/scala-3_0_2/core/src/test/scala-3/com/softwaremill/diffx/test/DiffTest.scala#L308)
• [x] unify test codebase (For now I duplicated all the tests for scala-3 in order to be sure that we won't be breaking any scala-2 code, that have to be unified before merging)
• [x] migrate scalatest module
• [x] migrate refined module
• [x] migrate cats module
• [x] migrate spec2 module
• [x] migrate utest module
• [x] migrate tagging module
• [x] migrate munit module
• [x] migrate js

[ghostbuster91]

This also fixes #265