cameraserver: Add watchdog timer for disconnect.

Bug: 228641945

Test: Add artifical delay of 2 seconds in disconnectImpl, see tombstone

Change-Id: I11254e04d9d883e839dc1a7eee309e249613957e
Signed-off-by: Jayant Chowdhary <jchowdhary@google.com>
(cherry picked from commit 48162a77)