[CSDiagnostics] Differentiate between key path type and value issues

Make sure that contextual mismatch uses a correct locator when
the issue is with key path value type instead of the key path
type.

lib/Sema/CSSimplify.cpp

@@ -6693,7 +6693,8 @@ bool ConstraintSystem::repairFailures(
     }
 
     conversionsOrFixes.push_back(IgnoreContextualType::create(
-        *this, lhs, rhs, keyPathLoc));
+        *this, lhs, rhs,
+        getConstraintLocator(keyPathLoc, ConstraintLocator::KeyPathValue)));
     break;
   }
   default: