Add an Open Remote Terminal button to access remote terminal sessions on devices

[davidebriani]

Building on top of #444, #445 and #446, the frontend can implement a button that allows users to open remote terminal sessions on devices that support the functionality.

The frontend can display the "Open remote terminal" button on each device page, if the device has the REMOTE_TERMINAL capability.
The button is disabled if the device is offline.

When the button is pressed, the frontend performs the requestForwarderSession GraphQL mutation:

• If the sessionStatus in the mutation’s response is not CONNECTED, it means that the device did not connect to the Forwarder yet and the session is not ready. The frontend then polls the GraphQL query forwarderSession until the status of the session is CONNECTED. In the mean time, it will display a loading state.
• If the session status is CONNECTED, the frontend composes the URL for the remote terminal session: https://<forwarder_host>:<forwarder_port>/v1/<session_token>/http/7681. The frontend then opens a new browser tab and navigates to the URL of the remote terminal session.

[davidebriani]

Closing as implemented by #472