This commit adds a menu item in the tray labeled "Tunnels", which shows
a submenu with available VPN tunnels and a checkbox indicating if the
tunnel is connected or disconnected. Clicking on a tunnel toggles its
connected/disconnected status.
This commit extracts the following functions from the button change
state callback:
- `IsTunnelConnected(name string) (bool, error)` - checks if the
tunnels is connected or returns an error
- `DisconnectTunnel(name string) error` - disconnects from the tunnel
or returns an error
- `ConnectTunnel(name string) error` - connects to the tunnel or
returns an error
- `ToggleTunnel(name string) error` - toggles the
connected/disconnected status of the tunnel
