[moblab] Add a service that can execute remote requests.

This service will allow users to execute pre-defined remote commands
on their moblabs, at the moment this is restricted to triggering
suite run requests but the number of types of request will be

There are more unit tests and testing to come, however this is
enough for a MVP.

TEST=build and run on local moblab

Change-Id: I2aebd909bd8f5ada09cab9cb410f1534acdcc21b
Reviewed-on: https://chromium-review.googlesource.com/1562602
Commit-Ready: Keith Haddow <haddowk@chromium.org>
Tested-by: Keith Haddow <haddowk@chromium.org>
Reviewed-by: Matt Mallett <mattmallett@chromium.org>
14 files changed