The default and only helper to run acceptance tests run them on the PHP
built-in web server. This commit introduces a new helper that can be
used to run them on an Apache web server instead.
This helper is meant to be used by the acceptance tests of apps that
require a multi-threaded web server to run (like Talk, due to its use of
long polling). To use the helper it is only needed to set it in the
Behat configuration for the acceptance tests of the app, as explained in
the "NextcloudTestServerContext" documentation.
It is assumed that the acceptance tests are run using the default setup,
and therefore inside a Docker container based on the image for
acceptance tests from Nextcloud. Due to that the helper is expected to
have root permissions, and thus it starts and stops the Apache web
server directly using "service start/stop apache2". In the same way it
also restores the owner and group for "apps", "config" and "data" to
"www-data", as it is the user that Apache sub-processes are run as.
Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>