6755: Remove individual RGBA sliders from editor color picker, add shift+rightclick/leftclick to copy/paste color in editor r=Jupeyy a=Robyt3
Remove the individual RGBA sliders for editor color pickers and only show one button that opens the color picker popup instead.
Decrease size of layer and point popups that previously had color properties which need less space now.
Support shift-rightclicking color picker buttons to copy the color to the clipboard in RRGGBBAA hex format.
Support shift-leftclicking color picker buttons to paste a color from the clipboard in RGB, RGBA, RRGGBB or RRGGBBAA format with optional leading `#` or `$`.
Screenshots:
- Before:
![screenshot_2023-06-20_20-39-43](https://github.com/ddnet/ddnet/assets/23437060/4a8b230c-a66b-4e2a-9744-cb5f80f6a799)
- After:
![screenshot_2023-06-20_20-40-00](https://github.com/ddnet/ddnet/assets/23437060/517f90cf-06a5-4332-9eb8-6a87cbc91b32)
- After (color picker open):
![screenshot_2023-06-25_17-35-55](https://github.com/ddnet/ddnet/assets/23437060/30320b56-e4cb-4e93-bf7b-8cfc8d96620b)
Suggested by `@HiRavie` in https://github.com/ddnet/ddnet/pull/6743#issuecomment-1593886873, though it was easier and also looks better to me when the color picker button has exactly the same size as the other value selectors.
## Checklist
- [X] Tested the change ingame
- [X] Provided screenshots if it is a visual change
- [ ] Tested in combination with possibly related configuration options
- [ ] Written a unit test (especially base/) or added coverage to integration test
- [ ] Considered possible null pointers and out of bounds array indexing
- [ ] Changed no physics that affect existing maps
- [ ] Tested the change with [ASan+UBSan or valgrind's memcheck](https://github.com/ddnet/ddnet/#using-addresssanitizer--undefinedbehavioursanitizer-or-valgrinds-memcheck) (optional)
Co-authored-by: Robert Müller <robytemueller@gmail.com>