workloads: add a new camera preview workload
workloads: add a new camera preview workload

This workload starts the camera app, waits for a few seconds and then starts
data collection (trace, energy etc).

Signed-off-by: Joel Fernandes <89f39a38232ac523c7644e47b6ca6563177e40b4@google.com>

credp/lisa,mdigiorgio/lisa,arnoldlu/lisa,arnoldlu/lisa,ARM-software/lisa,credp/lisa,credp/lisa,ARM-software/lisa,bjackman/lisa,mdigiorgio/lisa,ARM-software/lisa,credp/lisa,bjackman/lisa,ARM-software/lisa