Add benchmark for jobject functions

Measures performance of:
Add/RemoveLocalRef
Add/RemoveGlobalRef
Add/RemoveWeakGlobalRef
Decoding local, weak, global, handle scope jobjects.

N5 results:
benchmark    ns linear runtime
AddRemoveGlobal 476.7 ===========================
AddRemoveLocal  42.0 ==
AddRemoveWeakGlobal 519.7 ==============================
DecodeGlobal  69.9 ====
DecodeHandleScopeRef  38.9 ==
DecodeLocal  70.7 ====
DecodeWeakGlobal 119.7 ======

Change-Id: Iba014a9993909ee45fd52ae48d6dea8428a86bf2