[FIR2IR] Consider isExpect flag for generated synthetic functions

It's actual for value classes

^KT-51969 Fixed

compiler/testData/codegen/box/multiplatform/multiModule/valueClasses.kt

@@ -0,0 +1,19 @@
+// ISSUE: KT-51969
+// !LANGUAGE: +MultiPlatformProjects
+// TARGET_BACKEND: JVM_IR
+// WITH_STDLIB
+
+// MODULE: common
+// TARGET_PLATFORM: Common
+// FILE: expect.kt
+
+expect value class ExpectValue(val x: String)
+
+// MODULE: main()()(common)
+// TARGET_PLATFORM: JVM
+// FILE: actual.kt
+
+@JvmInline
+actual value class ExpectValue actual constructor(actual val x: String)
+
+fun box() = ExpectValue("OK").x