Determine (default) type of user using Element

[Half-Shot]

Follow-up on #252

I won't restate all the context in the previous issue, but we'd like to determine the default type of user (personal, workplace, community) that a homeserver is likely to host. EMS for instance is aware of the type of user based upon the product they have purchased (Element One, Element Home, Element Cloud are all personal products, Element Enterprise Cloud is workplace, and special cased homeservers like mozilla.org / kde.org are community).

We'd like to record this information in a way that all clients can access so they can show the ideal flow for the user. Note that this shouldn't be the only available flow, but I'd expect the design to heavily imply to new users that they should follow it (with the option to say "I know what I am doing").

@clokep already mentioned that we should ideally avoid configuring this in the homeserver itself and I am minded to agree.

The solution I'd prefer is using the client .well-known file to indicate to all clients, not just the user's hosted Element instance, that the user is of a given type. This could be a field such as io.element.user-type-hint which simple is one of three enums personal, community and workplace.

[karlabbott]

I've labeled this occasional as this would pretty much be a one-time setup thing.