MUONS: Action buttons on Script Console ribbon

As a muon instrument scientist, I would like a small number of buttons to be added to the Scripting Console to implement defined scripting actions.

The rationale for this feature is that many muon users do not have English as a first language. Explaining command syntax over the phone to non-native English speakers is often difficult. Providing users with some simple, basic scripting-related actions could be valuable to the user and to the instrument scientist, viz:
1. If the user is unfamiliar with the `genie_python` command syntax, he/she could press a button which would inject the command into the console and execute it.
1. In a remote support scenario, the instrument scientist could instruct the user to press the "blue" button (or whatever colour is appropriate). The could be especially import if the user needs to start or stop a run.

The actions to be implemented are a matter for discussion, but they could be as simple as `g.begin()`, `g.end()` and `help()`. The action buttons could be similar to the existing "Terminate" and "Ctrl+C" buttons. The buttons should be coloured, so that they are easily identifiable. We are not thinking of more than 4 or 5 extra buttons (not least, because we'll quickly run out of clear, distinct colours). It would be nice if the actions could be configurable but, if they have to be hard-coded, so be it. If hard-coded, the actions will need to be defined in discussion with scientists.

#### Acceptance Criteria
1. Action buttons are added to the scripting console ribbon (as many as reasonable given limitations of space and colour).
1. On pressing a console action button, a defined `genie_python` command (or script) is injected into the console and executed.

#### Notes
1. Ideally, the button would inject and execute the command. If it can only inject the command (leaving the user to press enter), that's OK.
1. Equally ideal would be configurable actions - so that each instrument can have its own actions. If this is not possible, then actions can be hard-coded.