[autotest] Enable provisioning Brillo device from autotest

This change adds the support of provision Brillo device from autotest. Methods
are added to adb_host, so machine_install knows how to provision a Brillo
device with given build, e.g., git_mnc-brillo-dev/dragonboard-userdebug/LATEST.

TEST=moblab setup, set build to git_mnc-brillo-dev/dragonboard-userdebug/LATEST
also make sure the change doesn't break Android provision

Change-Id: I299349301067572e7f4ee6792e19da3853e657f3
Reviewed-on: https://chromium-review.googlesource.com/315775
Commit-Ready: Dan Shi <dshi@google.com>
Tested-by: Dan Shi <dshi@google.com>
Reviewed-by: Simran Basi <sbasi@chromium.org>
2 files changed