UX: Enhance the webhook/deploykey walktrough

[Richard87]

Currently its very hard to see what is our content, and what is a screenshot from GitHub.

I Want to split the popup in 3 popups

1. Display Deploy key setup
2. Display Webhook setup
3. Bigger button to create "Apply Config" job

(make sure we our updating the URL between popups, and give a button to go forward and backwords, hint use useSearchParams() )

Also, I think we should use screenshots from GitHubs dark mode, or change the size of the screenshot to better separate it from our instructional text

DoD
Step by step wizard, configure webhook and deploy key