Use global shortcut to pcik on copy color

[wazeerc]

Is your feature request related to a problem? Please describe.
Not related to a problem but could massively improve the app's UX.

Describe the solution you'd like
Simplify the UX and workflow:

1. Set a keyboard shortcut (e.g. super + shift + e)
2. Automatically open the eyedropper
3. Automatically copies the hex code to the user's clipboard (default format can be set in settings)

Describe the impact of the feature on other users
This will reduce the number of clicks/interactions required to select a colour. Instead of opening the app, clicking on the dropper icon, then selecting a colour. These 3 actions can be bound to a single keyboard shortcut.

Additional context
The Microsoft PowerToys Color Picker works like this, refer to this GIF to get a better idea of what I'm suggesting. It would also be nice if we allow the user to set their preferred "activation behaviour".

P.S: I am new to Gnome and Rust but I am a click away if you need any clarifications or help with the UX or UI. Cheers!

[wazeerc]

@FineFindus

[FineFindus]

Thanks for the suggestion. This is partially already implemented (see #19). Running the background and launching on startup will be supported with the next release.

Automatically copying an color is a duplicate of #60.