Collaboration: C2/C3: Create new service for collaboration

[wekitecs]

Wrapper for PhotonEngine, also with base class to allow replacing photon with other, native implementations (e.g. mirror) as fallback.

Foresee functionality for:

• [ ] Session Management: Initiate a collaboration session by inviting team members or sharing join code, so that the participants can securely access the collaborative session.
• [ ] Match making: Allow matchmaking (e.g., 1st 4 into room 1, second 4 into room 2; e.g., pair graphic designer role and voice actor role and astronaut instructor role into one authoring session; e.g. pair learner with instructor into one learning session)

[fwild]

Matchmaking has priority low, but should of course be foreseen - and implemented if it is easy to do in one go.