[KLIB][tests] Reorganize "klib dump-metadata" tests

- Keep the test data under "native/native.tests/testData/klib/" dir
- Rename tests from "klib contents" to "klib dump-metadata"

native/native.tests/testData/klib/dump-metadata/builtinsSerializer/annotatedEnumEntry.txt

@@ -0,0 +1,11 @@
+    annotation class Anno constructor(value: String = ..., x: Int = ...) : Annotation {
+        val value: String
+        val x: Int
+    }
+    annotation class Bnno constructor() : Annotation
+    enum class Eee private constructor() : Enum<Eee> {
+        @Anno enum entry Entry1
+        enum entry Entry2
+        @Anno(value = "3") @Bnno enum entry Entry3
+        @Anno(value = "4", x = 4) enum entry Entry4
+    }