Add bluetooth_nrf52.py and other changes to support nRF52-based BLE HID server

BUG=chromium:923046
TEST=run bluetooth_AdapterHIDReports.ble_mouse on setup that includes
nRF52 devkit attached to Fizz.
e.g test_that -b vayne vaynemanor bluetooth_AdapterHIDReports.ble_mouse --autotest_dir=. --args "chameleon_host=vaynemanor-chameleon"

Change-Id: If8092b82f3420fa0e0e03c2c2c5bacf48df5f4a2
Reviewed-on: https://chromium-review.googlesource.com/1450029
Commit-Ready: Neeraj Poojary <npoojary@google.com>
Tested-by: Neeraj Poojary <npoojary@google.com>
Reviewed-by: Shyh-In Hwang <josephsih@chromium.org>
6 files changed