src: Mark surfaces with the 'remote' role if configuration file says so

As we don't have an explicit way to do it, like we have with the
protocol, we try to determine if the surface was being assigned a remote
output and use that, when the surface is created.

Bug-AGL: SPEC-3280

Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
Change-Id: Idd95acd9ae69c5ac37b50d447956b0ee46a94677