Extraction Engine: Fix extraction of labeled and non-local returns

idea/testData/refactoring/extractFunction/controlFlow/unextractable/unmatchedReturnTargets.kt

@@ -0,0 +1,7 @@
+// WITH_RUNTIME
+fun foo(a: Int): Int {
+    a.let {
+        <selection>if (it > 0) return@let it else return@foo -it</selection>
+    }
+    return 0
+}

idea/testData/refactoring/extractFunction/controlFlow/unextractable/unmatchedReturnTargets.kt.conflicts

@@ -0,0 +1 @@
+Selected code fragment has multiple exit points