Replace remaining fontawesome dropdown icons with SVG (#24455)

- Replace leftover dropdown triangles with SVG
- Replace remove icon with SVG and add styling for it:

<img width="817" alt="Screenshot 2023-05-01 at 00 40 05"
src="https://user-images.githubusercontent.com/115237/235379271-4674d4f7-b11e-4d6d-90f9-1478325443ca.png">
<img width="816" alt="Screenshot 2023-05-01 at 00 46 56"
src="https://user-images.githubusercontent.com/115237/235379451-b515afb3-9773-4f6f-a259-e7048235bcba.png">

web_src/css/base.css

@@ -2051,6 +2051,13 @@ a.ui.label:hover {
   color: var(--color-text);
 }
 
+.ui.labels a.active.label:hover,
+a.ui.active.label:hover {
+  background: var(--color-active);
+  border-color: var(--color-active);
+  color: var(--color-text);
+}
+
 .ui.label > .detail .icons {
   margin-right: 0.25em;
 }
@@ -2603,6 +2610,7 @@ table th[data-sortt-desc] .svg {
 }
 
 .ui.dropdown .svg.dropdown.icon,
+.ui.dropdown .svg.remove.icon,
 .svg.dropdown.icon {
   margin-top: 0 !important; /* reset the "ui.selection.dropdown > .dropdown.icon {margin-top}", for the Issue Dependencies dropdown */
   margin-right: -0.5rem !important; /* fix up SVG dropdown triangles because Fomantic thinks they are icon fonts */
@@ -2615,6 +2623,16 @@ table th[data-sortt-desc] .svg {
   top: 0 !important; /* reset the ".ui.selection.dropdown > .xxx.icon {top}" if the icon is svg instead of the fomantic icon */
 }
 
+.ui.selection.dropdown > .svg.remove.icon {
+  top: .5px;
+  right: 32px;
+  width: auto;
+}
+
+.ui.selection.dropdown > .svg.remove.icon:hover {
+  opacity: 1;
+}
+
 .ui.dropdown.no-text > .dropdown.icon {
   margin-left: 0 !important;
   margin-right: 0 !important;

web_src/css/features/gitgraph.css

@@ -46,10 +46,6 @@
   white-space: nowrap;
 }
 
-#git-graph-container #flow-select-refs-dropdown .dropdown.icon {
-  display: none;
-}
-
 #git-graph-container #flow-select-refs-dropdown .default.text {
   padding-top: 4px;
   padding-bottom: 4px;