Initially TESTSERVER_COMPOSE_FILE could be manually specified.
Later this got removed by accident. Re-enable this feature.
Furthermore, check if a module has a platform-specific compose file. If
not, fall back to a default docker-compose.yml. This is useful to
include testserver.pri from other modules, where no platform-specific
requirements are present, ie the image from provisioning works on all
platforms.
Change-Id: Icb92552fd61196be332b2431ab0f8a43b9157fc8
Reviewed-by: Ryan Chu <ryan.chu@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
e8bde992e0