[K2/N] Add klib contents serialization tests from old testinfra

Merge-request: KT-MR-8509
Merged-by: Vladimir Sukharev <Vladimir.Sukharev@jetbrains.com>

native/native.tests/testData/klibContents/builtinsSerializer/simple.kt

@@ -0,0 +1,11 @@
+package test
+
+class Class {
+    fun member() = null
+}
+
+fun function(int: Int, string: String = "default"): Class = Class()
+
+fun <T> T.extension(): T? = null
+
+val property: Unit = Unit