🪛 Replace imgui with egui

[tosti007]

This PR replaces imgui with egui for the visualizations.

Some notes:

1. I did try to make the code a bit cleaner along the way, but I think the visualization code can still use some de-duplication.
2. I removed the examples, as keeping them would mean having to rewrite the renderers to egui as well, we can add these again later is desired.
3. I kept the functionality as close as possible to the original, but I could not get the "focus" feature to work.
4. The memory chunk visualization uses the optimized scroll area logic, such that only the visible lines are drawn (this is a must for large blocks, otherwise FPS drops heavily).

[Jasper-Bekkers]

Happy to see this change, having egui integration for us is significantly more important and imgui was holding us back a bit.

Unfortunate that we're losing some of the samples, but if somebody needs them they're free to port them over to egui.

[tosti007]

After request of @Jasper-Bekkers, I also added a screenshot of the visualizers to the README.md

[fu5ha]

Nice :D

[Jasper-Bekkers]

I think the readme still needs some work because CI is complaining, but after that we can merge this and make a release