Adds Matterbridge service

[oliverlorenz]

I have implemented Matterbridge as a service and would like to contribute it.

As this is my first public MASH role, I would be very happy to have some feedback. If it is then considered okay, I would prefer the role to move into the MASH organisation.

I have also integrated the role into the mash-playbook. But I'm not sure if I've thought of everything. I would also be grateful for feedback on this :)

Best regards Oliver