Add kotlinp, a tool to print Kotlin metadata in class/module files

At the moment, it's not published anywhere, but that may change soon

 #KT-23198

libraries/tools/kotlinp/testData/SyntheticClass.kt

@@ -0,0 +1,7 @@
+fun f(a: AnnotationTarget): String? {
+    return when (a) {
+        AnnotationTarget.FUNCTION -> "1"
+        AnnotationTarget.PROPERTY -> "2"
+        else -> null
+    }
+}