cros_update: Migrate to chromite

This is mostly uses the cros_update files in the chromite.

BUG=chromium:1003986
TEST=./devserver_integration_test.py

Cq-Depend: chromium:1866027
Change-Id: Id9c3f6e4c6b8e08889ec96942f37f3e084380e9a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/1894676
Tested-by: Amin Hassani <ahassani@chromium.org>
Tested-by: Achuith Bhandarkar <achuith@chromium.org>
Commit-Queue: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
7 files changed