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/_review.less

@@ -96,7 +96,7 @@
       padding-top: 6px;
     }
 
-    &:after {
+    &::after {
       clear: both;
       content: "";
       display: block;