Backport #21990
- Use explicit avatar size so when JS copies the HTML, the size gets
copied with it
- Replace icon font use with SVG
- Improve styling and diff rendering
- Sort lists in `svg.js`
Fixes: https://github.com/go-gitea/gitea/issues/21924
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>