[Feature Request] Configurable key bindings

Tested in the latest Ubuntu 17.10 with the default desktop (Gnome) with the default Gnome Terminal 3.24, instead its intercepted and opens a file menu. I use ZSH but I doubt that's related.

I suggest we change the hotkey for Ubuntu 17.10

Also, related: typing exit and pressing enter should exit or display a text telling the user to type `.exit`, you know, because, UX

Start by locating the terminal input handling and command parsing for the integrated AWS shell, then check how the current hotkey behaves in Ubuntu 17.10 with Gnome Terminal. Done means the hotkey is configurable without being intercepted there, and typing `exit` either exits or clearly directs the user to type `.exit`.

Written by the indexing model from the issue text.