ExtractAPI: Add support for TypeLambdas
ExtractAPI: Add support for TypeLambdas

Before the new higher-kinded implementation this wasn't needed because
lambdas were just RefinedTypes.

sjrd/dotty,sjrd/dotty,som-snytt/dotty,dotty-staging/dotty,dotty-staging/dotty,som-snytt/dotty,som-snytt/dotty,lampepfl/dotty,sjrd/dotty,lampepfl/dotty,lampepfl/dotty,dotty-staging/dotty,som-snytt/dotty,lampepfl/dotty,sjrd/dotty,lampepfl/dotty,som-snytt/dotty,sjrd/dotty,dotty-staging/dotty,dotty-staging/dotty