Grant access to DMs in debusine.debian.net

After presenting debusine.debian.net to the Brazilian community, some DMs demonstrated interest in experimenting with it. They are really involved with the community and should become DDs any time soon, but right now they cannot use debusine.debian.net.

After talking to Raphael and Helmut, it was concluded that we may need a mechanism/policy/process to grant access to DMs, since they are not easily mapped to a salsa group. Raphael suggested to create this issue so we can discuss more broadly about this.

One possible solution discussed with Raphael is creating a salsa group controlled by Debusine people, and we map this group on the Debusine side. Whenever we get a request like this, we simply add the DMs (or even contributors without access to the archive if we judge so) to this group. WDYT?