Add FlexibleType support for scaladoc (#23320)

Scala Tooling Spree PR. //cc @KacperFKorban 

Fixes #22761

---------

Co-authored-by: Kacper Korban <[email protected]>

Author: 2m

scaladoc/src/dotty/tools/scaladoc/tasty/InkuireSupport.scala

@@ -315,6 +315,8 @@ trait InkuireSupport(using DocContext) extends Resources:
         inner(tpe, vars) //TODO [Inkuire] Repeated types
       case AnnotatedType(tpe, _) =>
         inner(tpe, vars)
+      case FlexibleType(tpe) =>
+        inner(tpe, vars)
       case tl @ TypeLambda(paramNames, _, resType) =>
         Inkuire.TypeLambda(paramNames.map(Inkuire.TypeLambda.argument), inner(resType, vars)) //TODO [Inkuire] Type bounds
       case pt @ PolyType(paramNames, _, resType) =>

scaladoc/src/dotty/tools/scaladoc/tasty/TypesSupport.scala

@@ -118,6 +118,8 @@ trait TypesSupport:
         inner(tpe, skipThisTypePrefix) :+ plain("*")
       case AnnotatedType(tpe, _) =>
         inner(tpe, skipThisTypePrefix)
+      case FlexibleType(tpe) =>
+        inner(tpe, skipThisTypePrefix)
       case tl @ TypeLambda(params, paramBounds, AppliedType(tpe, args))
         if paramBounds.forall { case TypeBounds(low, hi) => low.typeSymbol == defn.NothingClass && hi.typeSymbol == defn.AnyClass }
         && params.length == args.length