Add gestures to shortcut overlay

[pongloongyeat]

Problem

Hard to know what gestures do what. Might be obvious to the general user but this is hard for users who are new to using laptops/newcomers in general.

Proposal

Add gestures to the shortcut overlay. Suggested list of gestures to be added:

• Multitasking view
• Switch workspaces
• Scroll
• Delete current workspace (I'm not sure if there's such a gesture)

Possible issues

• Unlike shortcuts, it's hard to visualise and show a nice label for gestures. It probably has to be described i.e. "Swipe up with four fingers", etc.
• Looks out of place. Everything on the shortcut overlay are keyboard shortcuts. Having a trackpad gesture seems really out of place here.

Prior Art

None

[cassidyjames]

I definitely want to think through and sketch/prototype this before we get too far, but I agree it could make sense to show gestures here. They should similarly pick up the gestures as configured by the current user as well. My initial thought is adding a stack switcher up top (similar to the idea for #28), and have a Gestures page with these; that also gives us a bit more flexibility with the layout, as it doesn't need to strictly match the keyboard page.