JVM, JVM IR: report error if not all parts of multifile class are @JvmSynthetic

#KT-41884 Fixed

compiler/testData/codegen/bytecodeListing/multifileClasses/jvmSynthetic.kt

@@ -0,0 +1,18 @@
+// WITH_RUNTIME
+// FILE: f.kt
+
+@file:JvmName("Foo")
+@file:JvmMultifileClass
+@file:JvmSynthetic
+package test
+
+fun f() {}
+
+// FILE: g.kt
+
+@file:JvmName("Foo")
+@file:JvmMultifileClass
+@file:JvmSynthetic
+package test
+
+val g = ""