Merge pull request #6540 from alemannosara/part1

String `f` interpolator macro

Author: nicolasstucki

library/src-2.x/dotty/internal/StringContext.scala renamed to library/src-2.x/dotty/internal/StringContextMacro.scala

@@ -1,6 +1,6 @@
 package dotty.internal
 
-object StringContext {
+object StringContextMacro {
 
   @forceInline def f(sc: => scala.StringContext)(args: Any*): String =
     throw new Exception("non-boostrapped library")