Disable keypresses / controls with a flag

[crabdancing]

Checklist

• [X] I've looked through the documentation and existing open issues for similar feature requests.

Describe the feature request

Bottom looks really nice and gives a good persistent overview of the system state. I'd like to be able to set it as a VT login app, and just configure it so that the controls are disabled -- such that I don't have to worry about anyone messing with it (accidentally or otherwise). This would be pretty nice for getting a gestalt impression of server status on dedicated monitors, and if it was a first-class supported feature, it reduces the security concerns considerably. :)

[ClementTsang]

Hmm... and how would it be stopped? Do we leave ctrl-c as an exit option, or just rely on pkill or the like?

[crabdancing]

I think for a use case like this, it should be unresponsive to controls including Ctrl+C. Should still respond to actual SIGINT signal sent from another process, though.