Add regression tests for final expect classes overrides that change modality

KT-61840
Specifically see the comment:
https://youtrack.jetbrains.com/issue/KT-61840/K2-support-changes-in-overrides-of-fake-overrides-of-expect-declarations#focus=Comments-27-8077580.0-0

Review: https://jetbrains.team/p/kt/reviews/12147/timeline

compiler/testData/diagnostics/tests/multiplatform/changeModalityFromOpenToFinalInOverride_finalExpectClass_finalActualClass.kt

@@ -0,0 +1,16 @@
+// FIR_IDENTICAL
+// MODULE: m1-common
+// FILE: common.kt
+
+open class Base {
+    open fun foo() {}
+}
+
+expect class Foo : Base
+
+// MODULE: m2-jvm()()(m1-common)
+// FILE: jvm.kt
+
+actual class Foo : Base() {
+    final override fun foo() {}
+}

compiler/testData/diagnostics/tests/multiplatform/changeModalityFromOpenToFinalInOverride_finalExpectClass_openActualClass.kt

@@ -0,0 +1,16 @@
+// FIR_IDENTICAL
+// MODULE: m1-common
+// FILE: common.kt
+
+open class Base {
+    open fun foo() {}
+}
+
+expect class Foo : Base
+
+// MODULE: m2-jvm()()(m1-common)
+// FILE: jvm.kt
+
+actual open class Foo : Base() {
+    final override fun foo() {}
+}