[QoI] Fix position of the fix-it related to raw representable conversion

Part of the fix-it for conversion from optional to raw representable
was inserted at the incorrect position which produces invalid expression.

Resolves: rdar://problem/32431736
(cherry picked from commit 2bec75e)

Author: xedin

lib/Sema/CSDiag.cpp

@@ -3638,7 +3638,7 @@ static bool tryRawRepresentableFixIts(InFlightDiagnostic &diag,
                       toType, fromType)
         .highlight(exprRange)
         .fixItInsert(exprRange.Start, fixItBefore)
-        .fixItInsert(exprRange.End, fixItAfter);
+        .fixItInsertAfter(exprRange.End, fixItAfter);
     }
   };
 

test/Sema/enum_raw_representable.swift

@@ -97,11 +97,11 @@ func rdar32431736() {
 
   let myE1: E = items1.first
   // expected-error@-1 {{cannot convert value of type 'String?' to specified type 'E'}}
-  // expected-note@-2 {{construct 'E' from unwrapped 'String' value}} {{17-17=E(rawValue: }} {{24-24=!)}}
+  // expected-note@-2 {{construct 'E' from unwrapped 'String' value}} {{17-17=E(rawValue: }} {{29-29=!)}}
 
   let myE2: E = items2?.first
   // expected-error@-1 {{cannot convert value of type 'String?' to specified type 'E'}}
-  // expected-note@-2 {{construct 'E' from unwrapped 'String' value}} {{17-17=E(rawValue: (}} {{25-25=)!)}}
+  // expected-note@-2 {{construct 'E' from unwrapped 'String' value}} {{17-17=E(rawValue: (}} {{30-30=)!)}}
 }
 
 // rdar://problem/32431165 - improve diagnostic for raw representable argument mismatch