Expand how an individual user can allow room visitors to authenticate

[misslivirose]

Introduction
Hubs Cloud has a feature set available to administrators that gives them control over the user accounts that are able to access rooms on that particular server. This allows them to restrict access to rooms based on their own criteria, for example: having purchased a ticket to an event. We also have exploratory work into OAuth support on Hubs Cloud servers, and our Discord authentication on hubs.mozilla.com. This feature would unify the authentication opportunities into a single, easy-to-use portal configuration that a room owner would be able to specify for individual rooms that they create.

Example user stories
Callum enjoys using Hubs for meeting with groups of friends and has recently started using rooms that they create on hubs.mozilla.com for work meetings. They notice that a new Hubs update has been released that now has a room management portal. Callum explores the portal and notices that they can now restrict rooms to specific email addresses. Callum works with their IT group to set up the rooms that they use for work with their corporate SSO, and adds their family's email addresses to the private room that they use for their weekly hangouts. Callum appreciates that there is an extra layer of security over the rooms they create, and is able to start using Hubs for additional types of meetings at work.

┆Issue is synchronized with this Jira Task

[misslivirose]

Feedback from Blair in #54 as some thoughts on how this might be done:

"In addition to being able to restrict access to the server based on accounts, I would like to be able to create rooms that only are accessible from certain accounts.

Essentially, it would be good to have Google-doc like permissions for each room

• Accounts with full access (create, modify, etc) (I think the current promoted accounts to this)
• Accounts with read-only access (can't change) (I think if we turn edit features off, then this may be the normal)
• Explicit access by some people, or anyone with URL (we only do the later; need to say "only people with explicit perms can access)
• Access by those with accounts on server, or anyone with URL (even on servers with "only those with accounts can access, it might be nice to be able to have some "open rooms" that can be shared with others, without requiring accounts)"