Fix tooltips and issue dependency styles (#13458)

- Convert all tooltips to JS-based ones, fixing overflow issues
- Restyle issue dependencies/dependants
- Move popup styles to base style
- CSS Helper tweaks
- Unify pseudo element selectors and lint for it

Fixes: https://github.com/go-gitea/gitea/issues/13400

web_src/less/standalone/swagger.less

@@ -4,8 +4,8 @@ html {
 }
 
 *,
-*:before,
-*:after {
+*::before,
+*::after {
   box-sizing: inherit;
 }