Code Insight: "Generate toString" action

#KT-10309 Fixed

idea/testData/codeInsight/generate/toString/singleTemplate/superClassNoVars.kt.after

@@ -0,0 +1,15 @@
+// GENERATOR: SINGLE_TEMPLATE
+// GENERATE_SUPER_CALL
+open class X {
+    override fun toString() = super.toString()
+}
+
+class A : X() {
+    fun foo() {
+
+    }
+
+    <caret>override fun toString(): String{
+        return "A() ${super.toString()}"
+    }
+}