Implementing support for NFC observe mode, polling loop fingerprints

and field strength along with their associated APIs.

Bug: 294217286
Bug: 294435374
Bug: 296057223
Test: tested with CTS and manually
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:81080d559182483d9582dc8dc9ed75de3307c572)
Merged-In: I884527f9271a93997fa47b3764f9fa711cddb6f2

Change-Id: I884527f9271a93997fa47b3764f9fa711cddb6f2