Use LanguageFeatureSettings instead of JVM option for top level sealed classes

compiler/testData/diagnostics/tests/sourceCompatibility/noTopLevelSealedInheritance.kt

@@ -0,0 +1,5 @@
+// !LANGUAGE: -topLevelSealedInheritance
+
+sealed class Base
+
+class Derived : <!SEALED_SUPERTYPE!>Base<!>()

compiler/testData/diagnostics/tests/sourceCompatibility/noTopLevelSealedInheritance.txt

@@ -0,0 +1,15 @@
+package
+
+public sealed class Base {
+    private constructor Base()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class Derived : Base {
+    public constructor Derived()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}