[FIR-TEST] Add new testdata generated after changes in previous commit

compiler/testData/diagnostics/tests/override/ExtendFunctionClass.fir.kt

@@ -0,0 +1,9 @@
+package extendFunctionClass
+
+class A : Function1<Int, Int> {
+
+}
+
+class B : Function1<Int, Int> {
+    override fun invoke(p1 : Int) = p1
+}