Use matrix protocol and server for issues, pull requests and wiki

[Weasy666]

We should be able to use the matrix protocol and a server like timokoesters/conduit for managing and federating issues, pull requests and even the wiki.
I imagine this along the following line:

• a matrix room is the equivalent of one issue or one pull request.
• the comments on a issue or pull request are the messages in a room.
• mentions, reply-tos and reactions are already supported by the spec.
• assignees, labels, project, milestones and such stuff could maybe be added as a custom field.
• groups/organizations could be covered by the revamped communitys, that should then also, hopefully, allow to set permissions for members.
• the wiki could also simply be one room, with each message a wiki page. what needs to be investigated, is if it is possible for someone to edit the message of someone else, if not, then wiki-as-room with messages-as-pages is not feasible. As an alternative, the wiki could be a community and each room in it a page. then each message could be a set of changes to that page.
• another big question mark would be, how to integrate all this with git or another version control system. I think it could be especially tricky for diffs and inline comments on source code.