Interoperatibility with mobile messaging applications (Signal, Telegram, etc.)

Let’s collect some information on applications that we might want to include by default in Tails.

Blueprint: https://tails.boum.org/blueprint/mobile_messaging/

In our 2020-2022 roadmap, we've added 1 big thing among this one, #10491 (closed), and #18086.

Data points from user research:

• https://tails.boum.org/contribute/how/user_experience/interviews/daniel/
• Hot topics during the training in Mexico (#18922 (closed)) and Brazil (#19103 (closed))