Add support for server defined join address groups

[Josh65-2201]

I would like to be able to..

I would like if the server config could have predefined groups that can have user control visibility in addition to user adding there own

join_groups:
    group_name: (show _ as a space in the UI)
        "url/ip"

Is your feature request related to a problem? Please describe.

It very easy to lose groups and having some server defined ones give everyone viewing same data.

[AuroraLS3]

This has turned out to be surprisingly complicated since each server has its own join address list 🤔 I would assume server owner would like to configure all groups in one place on networks with multiple servers, but adding uuids to the config seems a bit cumbersome - and reusing one default group from the config for all servers doesn't seem to make sense