Press and hold a modifier key to see a cheatsheet of hotkey shortcuts

There are many hotkeys that exist throughout fluxer, and there are small hints throughout the app in relevant places to learn some of them, but others remain hidden and are harder to learn about. There isn't a quick and easy reference guide that can be accessed without stopping what you're doing for hotkeys.

Add a hotkey cheatsheet that can be quickly accessed from anywhere in the UI so that users can see a reference guide to learn about new hotkeys or remember hotkeys they are trying to learn and utilize.

A few simple examples are added.