Changes to SessionDetailsDTO: Support for hybrid labs

Description

The introduction of hybrid labs means the following can occur:

• A session can be normal (on campus) with all locations being physical.
• A session can be completely online (Only jitsi, MS teams, etc) which means that there are no rooms.
• A session can be hybrid, physical locations + online meetings.

Labracore does not currently support this, the following needs to be changed.

• The DTO's + entity needs to be changed to accomodate this.
• A possible DB migration to include associated online modes in the DTO. ??????????????????