Beta support of peer video calls, some minor bug fixes

Features

• SI-2332 – Beta support of peer to peer video calls

Bug Fixes

• SI-2510 – When rejoining a conference call any joiners or leavers were not reported
• SI-2522 – Restoring a backup with attachments now handles the error case better
• SI-2535 – The favourite icon should not show for a conference call
• SI-2539 – Corrected the colours in the conference room info
• SI-2542 – We now requery a group that we have ‘left’ to find the real reason – was the group disbanded or were you removed