From now on we are able to access local settings (settings and global settings)
on the nim side, not only through the qml.
This change is required as part of the feature issue-2675.
Since `src/status` was Qt dependant part because of the following foundation files:
- /src/status/tasks/marathon/mailserver/controller.nim
- /src/status/signals/core.nim
- /src/status/tasks/marathon/mailserver/events.nim
- /src/status/tasks/qt.nim
and because logic related classes like:
- /src/status/chat.nim
this commit made that part Qt independant.
New layer `src/app_service` is introduced and above mentioned foundation files
are moved there. As well as corresponding logic for requested services.
Communication between logical parts on the high level is as follows:
- `src/app` => `src/app_service` => `src/status` => `src/app`
- `src/app` => `src/status` => `src/app`
Fixes: #3376
