[Refactoring] Add try for extracted function call

If we're extracting a function that throws, add
a `try` to the call.

Author: hamishknight

lib/IDE/Refactoring.cpp

@@ -1332,6 +1332,10 @@ bool RefactoringActionExtractFunction::performChange() {
     llvm::raw_svector_ostream OS(Buffer);
     if (RangeInfo.exit() == ExitState::Positive)
       OS << tok::kw_return <<" ";
+
+    if (RangeInfo.UnhandledEffects.contains(EffectKind::Throws))
+      OS << tok::kw_try << " ";
+
     CallNameOffset = Buffer.size() - ReplaceBegin;
     OS << PreferredName << "(";
     for (auto &RD : Parameters) {

test/refactoring/ExtractFunction/Outputs/throw_errors/L13-17.swift.expected

@@ -18,6 +18,6 @@ func foo2() throws {
   do {
     try foo1()
   } catch {}
-  new_name()
+  try new_name()
 }
 

test/refactoring/ExtractFunction/Outputs/throw_errors/L8-8.swift.expected

@@ -9,7 +9,7 @@ return try foo1()
 }
 
 func foo2() throws {
-  new_name()
+  try new_name()
   try! foo1()
   do {
     try foo1()