Add shortcut to add emotes from within the active text input

[lostdesign]

Should be able to trigger an overlay getting an emote from anywhere without going back to the app. Basically having a search on shortcut with a tiny preview.

[lostdesign]

Basically register a global shortcut https://github.com/electron/electron/blob/master/docs/api/global-shortcut.md which creates a new window.