room client in Go

[cryptix]

Just a tracking issue, there is no room client in Go as of yet. Could increase the efficiency and turnaround time of our tests, tho and might enable much better performance testing, using tools of the toolchain itself.

Two things to consider:

1. writing a muxrpc plugin for it in this repo, would mean pulling in all these dependencies into go-ssb.
2. Inversely, adding it to go-ssb would pull in all of go-ssb here, including all the (custom) database stuff and their deps.

Go's go.mod file doesn't differentiate between testing dependencies and while unused wouldn't be build in the server, they will still be fetched. Might make sense to have that code as a third standalone module.

[cryptix]

I think a good starting point would just be v1 code for tunnel.connect without all the invite creation and alias management bells and whistles. Basically it would be cool but not needed if go-ssb can act as a regular guest.

[cryptix]

This now partially exists in https://github.com/cryptoscope/ssb/pull/90