[autotest] Fetching jobs from global AFE to moblab

To scale autotest with sharding jobs and hosts need to be fetched by
the shards. This adds the fetching-functionality on the shard side.

TEST=Ran suites and tried scheduling dummy on global and fetching it

Change-Id: I54ac73e07027e36982e18eb606cdf5958c8c6c89
Reviewed-on: https://chromium-review.googlesource.com/212725
Reviewed-by: Fang Deng <fdeng@chromium.org>
Commit-Queue: Jakob Jülich <jakobjuelich@chromium.org>
Tested-by: Jakob Jülich <jakobjuelich@chromium.org>
8 files changed