Fix nullability quick-fixes with implicit receiver #KT-17726 Fixed

idea/testData/quickfix/nullables/unsafeInfixCall/unsafeInvokeWithImplicitReceiver.kt

@@ -0,0 +1,9 @@
+// "Replace with safe (?.) call" "false"
+// ACTION: Add non-null asserted (!!) call
+// ACTION: Convert to block body
+// ACTION: Replace overloaded operator with function call
+// ACTION: Replace with safe (this?.) call
+// ACTION: Wrap with '?.let { ... }' call
+// ERROR: Only safe (?.) or non-null asserted (!!.) calls are allowed on a nullable receiver of type String?
+
+fun String?.foo(exec: (String.() -> Unit)) = exec<caret>()