[NAN] Use a hidden class for peer ID opaque handle

Results in clearer run-time exception (relatively to using Integer).

(cherry-pick of commit 57db2b3eea5333e5ee144ea29e4a4af02fae7309)

Bug: 31689166
Test: unit-tests + integrated (sl4a).
Change-Id: I79d0e8061204834b9775b02d503cb18fd03ed8c6
2 files changed