feature request: multi-magit (cross-repo aggregated status buffers) functionality

[sielicki]

Context:

• https://github.com/luismbo/multi-magit

• See discussion/screenshots here: A magit-status for multiple repositories magit/magit#3295

edamagit should have a performance advantage over emacs magit in terms of the ability to parallelize the work and/or incur less overhead for the generation of each heading, and that might make this viable to implement.