Bluetooth: Add BTC support in Bluedroid.

Provides an interface to get HCI commands/events
for Bluetooth WLAN coexistance.

Change-Id: I1662eb2c3f60b81dc27dad79350ef5ce94b8ae51
(cherry picked from commit 8b4649bdacd314c2b5f80b9a71a9badcb942d1a9)
(cherry picked from commit 20142ff996cc0081b2e25816828e07841afe4e17)
(cherry picked from commit b5c6cd0fe551240d351d6a63912c106643c55a35)