[NAN] Removed NAN event registration - dispatch all callbacks. [DO NOT MERGE]

All events dispatched by default - there's no reason to ignore events.
The specific identity changed events for which there are use-cases to
get or ignore is controlled through a new configuration.

Bug: 27607613
Change-Id: I289a36157b55270c58311a016ef79f8746e0e0a0
4 files changed