FIR checker: add diagnostic OVERRIDING_FINAL_MEMBER

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

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

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

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 open class A {
     final fun foo() {}
 }

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

@@ -5,7 +5,7 @@ class Foo {
 
 class Bar : Foo() {
     override fun openFoo() {}
-    override fun finalFoo() {}
+    <!OVERRIDING_FINAL_MEMBER!>override<!> fun finalFoo() {}
 }