Override Members: Allow overriding virtual synthetic members (e.g. equals(), hashCode(), toString(), etc.) in data classes

#KT-15563 Fixed

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

@@ -0,0 +1,5 @@
+data class Foo(val name: String) {
+    override fun equals(other: Any?): Boolean {
+        <selection>return super.equals(other)</selection>
+    }
+}