CameraService: Adds support for longshot mode

- This change introduces additional functionality inside
  CameraClient for supporting continuous compressed data
  callbacks. This is needed for 'Burst/Long shot' mode
  where we could have indefinite number of callbacks after
  capture is triggered.

(cherrypicked from commit e4f502aa7cbe8875e8a1589024cdcf227c228a2b)

Change-Id: Ia18ca9bdda7736c679db557e510870115089537a