JVM IR: Create non-synthetic multifile parts for -Xmultifile-parts-inherit

compiler/testData/codegen/bytecodeText/flagsInMultiFileInherit.kt

@@ -0,0 +1,16 @@
+// !INHERIT_MULTIFILE_PARTS
+@file:kotlin.jvm.JvmMultifileClass
+@file:kotlin.jvm.JvmName("Test")
+
+fun foo() {
+
+}
+
+
+/* ACC_PUBLIC ACC_FINAL ACC_SUPER */
+// 1 access flags 0x31
+// 1 public final class Test extends Test__FlagsInMultiFileInheritKt
+
+/* ACC_SUPER */
+// 1 access flags 0x20
+// 1 class Test__FlagsInMultiFileInheritKt