This patch adds a hover background for the wiki row in wiki list page,
which make its behavior more close to repo's file list page.
This patch also make the wiki-git-entry visible on the row is hovered
instead of the cel, so users won't be confused since the 'grid' is not
visible from the web page.
After the patch: (when the wiki named 'Home' is hovered)
![image](https://github.com/go-gitea/gitea/assets/10095765/f6c67c41-ad54-4ce4-a3b1-8c7551396ce0)
Close #20976
Close #20975
1. Fix the bug: the TOC in footer was incorrectly rendered as main
content's TOC
2. Fix the layout: on mobile, the TOC is put above the main content,
while the sidebar is put below the main content
3. Auto collapse the TOC on mobile
ps: many styles of "wiki.css" are moved from old css files, so leave
nits to following PRs.