Adds a feature similar to this https://github.blog/changelog/2021-11-24-specify-theme-context-for-images-in-markdown/ , by adding styles to elements which `src` or `href` attribute ends with `#light-mode-only` or `#dark-mode-only`. To improve compability, the github variants with the `gh-` prefix are also contained.
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/3985
Reviewed-by: 0ko <0ko@noreply.codeberg.org>
Co-authored-by: Mai-Lapyst <mai-lapyst@noreply.codeberg.org>
Co-committed-by: Mai-Lapyst <mai-lapyst@noreply.codeberg.org>
