contint::localvhost easily setup an apache listener

This generalized the QUnit vhost listening on localhost.  To run browser
tests, I would need as well a vhost listening on localhost and pointing
to some document root.

I simply converted the existing Apache conf for QUnit to be a template,
the class contint::localvhost let us fill the placeholders.

The QUnit vhost has been migrated to use the new class.

Apache 'Listen' statements are under /etc/apache2/conf.d/

bug: 54385
Change-Id: I3e17c2ab82fbbab5be654f48ca55cca98070ba40
Merge "contint::localvhost easily setup an apache listener" into production