Scala 3 support

[Tylerwbrown]

Is there an existing issue for this?

• [X] I have searched the existing issues

What is the missing lexer?

The main issue I've noticed is that : seems to be universally treated as a type annotation, while in Scala 3 it can also be used to denote blocks (essentially as an alternative to {}). I've attached some colon vs brace comparisons using the chroma playground.

Links to existing syntax definitions

https://docs.scala-lang.org/scala3/reference/syntax.html