Add toString() to Any, fix all tests

#KT-4517 Fixed

idea/testData/codeInsight/overrideImplement/multiOverride.kt.after

@@ -17,4 +17,7 @@ class C : A {
     override fun hashCode(): Int {
         return super<A>.hashCode()
     }
+    override fun toString(): String {
+        return super<A>.toString()
+    }
 }