Replace Pidgin: refine blueprint
_Originally created by @Dr_Whax on [#11686 (Redmine)](https://public-redmine-archive.tails.boum.org/code/issues/11686)_
Refining the blueprint to replace Pidgin hopefully one day.
Former team: drwhax, sycamoreone
Blueprint: https://tails.boum.org/blueprint/replace_Pidgin/
Parent Task: tails/tails#8573
### Related issues
- **Blocked by** tails/tails#15816
issue