refactor(icons): replace local brand SVGs with FA5 classes

Unify social/OAuth/contact icons on the global Font Awesome 5.15.4 pack,
add aksrt_render_social_links for author hero, enqueue FA on admin SPA,
and delete assets/img/icons.

assets/css/routes/profile/lists.css

@@ -537,9 +537,9 @@
   color: var(--color-ink);
   flex-shrink: 0;
 }
-.binding-item__icon svg {
-  width: 100%;
-  height: 100%;
+.binding-item__icon i {
+  font-size: 22px;
+  line-height: 1;
 }
 .binding-item__meta {
   display: flex;