Meeting customization

[edemaine]

Now that meetings have secret keys (#144), we can add meeting-specific customization:

• Setting default sort for a meeting
• Setting default Jitsi, Cocreate, etc. servers (Custom servers #30)
• Default room template (Default room structure / templates #47)
• Add/remove custom tab types from TabNew? (e.g. disable games or other things we add support for that aren't always relevant)
• Locking down permissions (Meeting Permissions tab #65), e.g., prevent normal users from creating/archiving/unarchiving rooms or adding tabs?
• Defaults for additional interface settings (Additional interface settings #132)

[mehtank]

Additional meeting-level settings [ possibly meta-configurable via Config options depending on how much customizability you want to enable on the main server vs self-hosted servers ]:

• Header icon
  • URL to image
  • Alternate dark-mode icon
  • Header icon width
  • Link
  • Hover tooltip
  • Favicon?
• Welcome
  • Custom inlined HTML added somewhere in the existing text
  • IFramed link replacing the welcome page altogether
• Chat infrastructure [ e.g. external RocketChat / Discord-via-titanembed / ?? ]
  • IFrameable URL to replace default top-level "meeting chat"
  • some way [ API calls? URL mangler? ] to create / refer to new room-level chats

[mehtank]

* Setting default sort for a meeting

The code for this already existed but wasn't accessible. This can now be set (via API, no UI yet) with d437c81 in #175