Introduce FIR_IDENTICAL for FIR vs old frontend tests #KT-36879 Fixed

compiler/testData/diagnostics/tests/j+k/genericConstructor/selfTypes.fir.kt

@@ -1,19 +0,0 @@
-// !DIAGNOSTICS: -UNUSED_VARIABLE
-// FILE: R.java
-public class R<T extends R<T>> {
-    public <F extends R<F>> R(F x) {
-    }
-}
-
-// FILE: RImpl.java
-public class RImpl extends R<RImpl> {
-    public RImpl() {
-        <RImpl>super(null);
-    }
-}
-
-// FILE: main.kt
-fun test() {
-    val x: R<RImpl> = R(RImpl())
-    R<RImpl, RImpl>(RImpl())
-}

compiler/testData/diagnostics/tests/j+k/genericConstructor/selfTypes.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // !DIAGNOSTICS: -UNUSED_VARIABLE
 // FILE: R.java
 public class R<T extends R<T>> {