Draft: beginners/getting_started: Update the tutorial
The Getting Started tutorial for beginners is severely outdated since the default project template has changed. I'm following it and updating alongside to make sure it actually works.
There are both UI, code and explanation changes, as well as updated images in both light and dark variants.
Supersedes MRs (unless they land first): !116 (closed), !122, !123, !124, !125, !126
Related MRs: !89 (closed), !99, !103 (closed), !105, !117 (closed), !129, !136 (merged)