Decide if we want to host a Mumble server for the project

See #9851-note_3. The alternative would be ad-hoc Mumble servers run from Tails.

Original created by @sajolida on 11003 (Redmine)

Edited Nov 22, 2019 by intrigeri

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information