Make SVG in dropdown menu have the same margin-right as IMG (#24316)

Fix #24226



![image](https://user-images.githubusercontent.com/2114189/234167393-0fe36a0d-29c9-46b6-b71d-52436f2b27f3.png)

Co-authored-by: silverwind <me@silverwind.io>

web_src/css/base.css

@@ -864,6 +864,9 @@ a.label,
   margin-top: -0.25rem;
   margin-bottom: -0.25rem;
 }
+.ui.dropdown .menu > .item > svg {
+  margin-right: .78rem; /* use the same margin as for <img> */
+}
 
 .ui.selection.dropdown .menu > .item {
   border-color: var(--color-secondary);