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

compiler/testData/diagnostics/testsWithStdLib/multiplatform/jvmOverloads.fir.kt

@@ -1,11 +0,0 @@
-// !LANGUAGE: +MultiPlatformProjects
-// MODULE: m1-common
-// FILE: common.kt
-
-expect fun foo(x: String, y: Int = -1)
-
-// MODULE: m2-jvm(m1-common)
-// FILE: jvm.kt
-
-@JvmOverloads
-actual fun foo(x: String, y: Int) {}

compiler/testData/diagnostics/testsWithStdLib/multiplatform/jvmOverloads.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // !LANGUAGE: +MultiPlatformProjects
 // MODULE: m1-common
 // FILE: common.kt