Connect EVSManager to EVS driver asynchonously

If the manager trys to connect to the driver before a thread is available
in the thread pool, the manager will stall for one second at a time until
the driver responds because handling an async resopnse requires a thread
from the thread pool.
To avoid this, we fire off the service connection and registration in a
background thread and then immediately add the main thread to the pool
so it can handle the responses.

Bug: 69228960
Test: Run android.automotive.evs.manager@1.0 on Mojave and check lshal
Change-Id: I5ddf183f666a30f94d79c656cf257c26e061ad9f
1 file changed