Add quick fixes for mod/rem migration

- Remove 'operator' modifier
 - Rename operator 'mod/modAssign' to 'rem/remAssign'

idea/testData/quickfix/renameToRem/modAsExtension.kt

@@ -0,0 +1,9 @@
+// "Rename to 'rem'" "true"
+
+object A
+operator<caret> fun A.mod(x: Int) {}
+
+fun test() {
+    A.mod(3)
+    A % 2
+}