Refactor OverrideResolver.checkOverrideForMember()

Create CheckOverrideReportStrategy interface to report override errors
(will be used later for synthesized members override checks).

Add diagnostic test on OVERRIDING_FINAL_MEMBER, as no such test happened
to exist before.

compiler/testData/diagnostics/tests/override/OverridingFinalMember.kt

@@ -0,0 +1,7 @@
+open class A {
+    final fun foo() {}
+}
+
+class B : A() {
+    <!OVERRIDING_FINAL_MEMBER!>override<!> fun foo() {}
+}