Sema: Refactor TypeCheckEffects.cpp in preparation for 'reasync' checking

Author: slavapestov

include/swift/AST/DiagnosticsSema.def

@@ -4093,7 +4093,7 @@ NOTE(because_rethrows_argument_throws,none,
 NOTE(because_rethrows_default_argument_throws,none,
      "call is to 'rethrows' function, but a defaulted argument function"
      " can throw", ())
-NOTE(because_rethrows_default_conformance_throws,none,
+NOTE(because_rethrows_conformance_throws,none,
      "call is to 'rethrows' function, but a conformance has a throwing witness", ())
 
 ERROR(throwing_call_in_nonthrowing_autoclosure,none,