[JVM IR] Make file classes with all private members package-private

compiler/testData/codegen/bytecodeListing/fileClassWithPrivateDeclarationsOnly_after.kt

@@ -0,0 +1,14 @@
+// WITH_RUNTIME
+// IGNORE_BACKEND: JVM
+// !LANGUAGE: +PackagePrivateFileClassesWithAllPrivateMembers
+
+private fun f() {
+}
+
+private val a = Unit
+private val b by lazy { Unit }
+
+@Suppress("INVISIBLE_MEMBER", "INVISIBLE_REFERENCE")
+@kotlin.internal.InlineOnly
+public fun g() {
+}