FIR: rename HIDDEN to INVISIBLE_REFERENCE

Some of them should be INVISIBLE_MEMBER though

compiler/testData/diagnostics/tests/enum/ConstructorCallFromOutside.fir.kt

@@ -6,5 +6,5 @@ enum class A(val c: Int) {
 
 fun createA(): A {
     // Error should be here!
-    return <!HIDDEN!>A<!>(10)
+    return <!INVISIBLE_REFERENCE!>A<!>(10)
 }

compiler/testData/diagnostics/tests/enum/inheritanceFromEnum.fir.kt

@@ -8,6 +8,6 @@ open enum class MyEnum() {
 
 enum class MyEnum2() {}
 
-class MyClass(): <!HIDDEN!>MyEnum2<!>() {}
+class MyClass(): <!INVISIBLE_REFERENCE!>MyEnum2<!>() {}
 
 class MyClass2(): <!UNRESOLVED_REFERENCE!>MyJavaEnum<!>() {}