Implements the front end of the FSM, with buttons/labels indicating the states and clickable transitions that the user can use to move from one state to another. The layout should be whatever is useful, but in principle it should represent the FSM described in the https://github.com/DUNE-DAQ/drunc/wiki/FSM .

The FSM structure cannot be retrieved in full from the Controller, so the states and the transitions will need to be hardcoded - althgouh the front end representation should be flexible enough so that using a different FSM will still render fine.

No actual link with the backend is to be done at this time.