Connect PbapClient Profile

Update code on CarKitt to appropriately connect the pbapClient
connection when another bluetooth connection is made or the adapter is
powered on.  This logic is necessary since pbapClient doesn't accept
incomming connections and the bluetooth connect command may not have
originated from CarKitt.

bug: 28249138
Change-Id: Iaf15ece5115b2f3cf6ef45af1d6ab8da17e0c303
(cherry picked from commit 8b0649c5b76fb40fe0acb7772a71fa3ca727c34e)