[FE] Make constructors of sealed classes protected instead of internal

idea/testData/decompiler/stubBuilder/Sealed/Sealed.txt

@@ -5,7 +5,7 @@ PsiJetFileStubImpl[package=test]
   CLASS[fqName=test.Sealed, isEnumEntry=false, isInterface=false, isLocal=false, isTopLevel=true, name=Sealed, superNames=[]]
     MODIFIER_LIST[public sealed]
     PRIMARY_CONSTRUCTOR
-      MODIFIER_LIST[internal]
+      MODIFIER_LIST[protected]
       VALUE_PARAMETER_LIST
     CLASS_BODY
       CLASS[fqName=test.Sealed.Nested, isEnumEntry=false, isInterface=false, isLocal=false, isTopLevel=false, name=Nested, superNames=[Sealed]]

idea/testData/quickfix/addDataModifier/sealed.kt

@@ -5,6 +5,7 @@
 // ACTION: Create member function 'Foo.component2'
 // ACTION: Enable a trailing comma by default in the formatter
 // ACTION: Put arguments on separate lines
+// ERROR: Cannot access '<init>': it is protected in 'Foo'
 // ERROR: Destructuring declaration initializer of type Foo must have a 'component1()' function
 // ERROR: Destructuring declaration initializer of type Foo must have a 'component2()' function
 // ERROR: Sealed types cannot be instantiated