Remove fomantic button module (#30475)

CSS-only module. Button colors are reduced to this:

<img width="639" alt="Screenshot 2024-04-14 at 15 36 07"
src="882d6c02-d1de-44f2-b707-db02a9f5070d">

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

web_src/css/modules/modal.css

@@ -10,6 +10,10 @@
   top: 1.2em;
 }
 
+.ui.modal > .close.inside {
+  color: inherit;
+}
+
 .ui.modal > .close.icon[height="16"] {
   top: 0.7em; /* fomantic uses absolute layout, so if we have special icon size, it needs this trick to align vertically */
   color: var(--color-text-dark);