KT-6632 "Convert to extension" intention should not be available on methods that override or implement a superclass method

#KT-6632 Fixed

idea/testData/intentions/declarations/convertMemberToExtension/override.kt

@@ -0,0 +1,9 @@
+// IS_APPLICABLE: false
+trait I {
+    fun foo()
+}
+
+class C : I {
+    override fun <caret>foo() {
+    }
+}