Add syncthingctl to toltec

[mooomooo]

Package information
syncthingctl (from https://github.com/Martchus/syncthingtray)

Reason for addition
This is a CLI that orchestrates syncthing, which is already in the repo. With it, it'd be possible to configure / manage syncthing via an on-device terminal, without needing a browser or another computer on the same network to access the web interface.