Remove nsquare problem when there are many subscribers

[rdeoliv]

Problem:
In the case where there is a high number of subscribers for the same asset, they face the NSquare problem. This is because all subscriber presence actions are being propagated to everyone else subsribed to the channel.

Proposed solution:
We need to add a specific profile for Subscriber-only permission (i.e. without presence publish and presence subscribe)
Those subscribers will get whatever resolution the publisher is providing and are not able to request new resolution.

Side comment:
We could think of creating a Main Subscriber which would be the only client which can request better resolution, but we need to think about how the handover work or what happens if that main subscriber leaves.

┆Issue is synchronized with this Jira Task by Unito