quickfix for usages of operators that don't have the proper annotation

idea/testData/quickfix/modifiers/operatorModifier.kt

@@ -0,0 +1,8 @@
+// "Add 'operator' modifier" "true"
+class A {
+    fun plus(a: A): A = A()
+}
+
+fun foo() {
+    A() <caret>+ A()
+}