Refine modality of fake overrides inherited from abstract expected members

In an open expected class inheriting an expected interface, abstract
members are now inherited as _open_ fake overrides, not final. Final was
technically safer but also stricter and thus could be unexpected by the
user. In a final class, abstract members are still inherited as _final_
fake overrides. So, the general rule is now the following: the modality
of an expected fake override, which overrides only abstract members, in
a non-abstract class is equal to the modality of that class

 #KT-22031 Fixed

compiler/testData/diagnostics/tests/multiplatform/headerClass/dontOverrideMethodsFromInterfaceInCommonCode.txt

@@ -17,14 +17,14 @@ public interface Foo {
 
 public final expect class ImplicitFoo : Foo {
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public abstract override /*1*/ /*fake_override*/ fun foo(): kotlin.Unit
+    public final override /*1*/ /*fake_override*/ fun foo(): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }
 
 public final expect class ImplicitFooCheck : Foo {
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public abstract override /*1*/ /*fake_override*/ fun foo(): kotlin.Unit
+    public final override /*1*/ /*fake_override*/ fun foo(): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }

compiler/testData/diagnostics/tests/multiplatform/headerClass/extendExpectedClassWithAbstractMember.kt

@@ -9,7 +9,7 @@ expect open class BaseAImpl() : BaseA
 
 class DerivedA1 : BaseAImpl()
 class DerivedA2 : BaseAImpl() {
-    <!OVERRIDING_FINAL_MEMBER!>override<!> fun foo() = super.foo()
+    override fun foo() = super.foo()
 }
 
 
@@ -21,7 +21,7 @@ expect open class BaseBImpl() : BaseB
 
 class DerivedB1 : BaseBImpl()
 class DerivedB2 : BaseBImpl() {
-    <!OVERRIDING_FINAL_MEMBER!>override<!> fun foo() = super.foo()
+    override fun foo() = super.foo()
 }
 
 
@@ -53,3 +53,10 @@ expect interface BaseE {
 sealed class BaseEImpl() : BaseE {
     fun bar() = super.<!ABSTRACT_SUPER_CALL!>foo<!>()
 }
+
+
+
+expect interface BaseF {
+    fun foo()
+}
+expect class BaseFImpl() : BaseF

compiler/testData/diagnostics/tests/multiplatform/headerClass/extendExpectedClassWithAbstractMember.txt

@@ -11,7 +11,7 @@ public abstract expect class BaseA {
 public open expect class BaseAImpl : BaseA {
     public constructor BaseAImpl()
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public final expect override /*1*/ /*fake_override*/ fun foo(): kotlin.Unit
+    public open expect override /*1*/ /*fake_override*/ fun foo(): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }
@@ -26,7 +26,7 @@ public expect interface BaseB {
 public open expect class BaseBImpl : BaseB {
     public constructor BaseBImpl()
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public final expect override /*1*/ /*fake_override*/ fun foo(): kotlin.Unit
+    public open expect override /*1*/ /*fake_override*/ fun foo(): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }
@@ -78,10 +78,25 @@ public sealed class BaseEImpl : BaseE {
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }
 
+public expect interface BaseF {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract expect fun foo(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final expect class BaseFImpl : BaseF {
+    public constructor BaseFImpl()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public final expect override /*1*/ /*fake_override*/ fun foo(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
 public final class DerivedA1 : BaseAImpl {
     public constructor DerivedA1()
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public final expect override /*1*/ /*fake_override*/ fun foo(): kotlin.Unit
+    public open expect override /*1*/ /*fake_override*/ fun foo(): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }
@@ -97,7 +112,7 @@ public final class DerivedA2 : BaseAImpl {
 public final class DerivedB1 : BaseBImpl {
     public constructor DerivedB1()
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public final expect override /*1*/ /*fake_override*/ fun foo(): kotlin.Unit
+    public open expect override /*1*/ /*fake_override*/ fun foo(): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }