Autotest: Add Django readonly database access.

Add a settings_readonly and a setup_django_readonly_environment.py so readonly
access through Django to the database can be done.

BUG=chromium:248363
DEPLOY=none
TEST=Ran the Autotest frontend server and nothing exploded.

Change-Id: I60a8522200352afafd5a194080cd36b48656c188
Reviewed-on: https://gerrit.chromium.org/gerrit/58150
Reviewed-by: Dennis Jeffrey <dennisjeffrey@chromium.org>
Reviewed-by: Dan Shi <dshi@chromium.org>
Commit-Queue: Keyar Hood <keyar@chromium.org>
Tested-by: Keyar Hood <keyar@chromium.org>
2 files changed