[Glitch] Add keyboard shortcut info banner to the boosting preferences section

Port 20961c7538 to glitch-soc

Signed-off-by: Claire <claire.github-309c@sitedethib.com>

app/javascript/flavours/glitch/styles/admin.scss

@@ -488,6 +488,14 @@ body,
   }
 }
 
+kbd {
+  font-family: Courier, monospace;
+  background-color: color.change($ui-secondary-color, $alpha: 0.1);
+  padding: 4px;
+  padding-bottom: 2px;
+  border-radius: 5px;
+}
+
 .filters {
   display: flex;
   flex-wrap: wrap;

app/javascript/flavours/glitch/styles/forms.scss

@@ -755,6 +755,12 @@ code {
     display: none;
   }
 
+  &.hidden-on-touch-devices {
+    @media screen and (pointer: coarse) {
+      display: none;
+    }
+  }
+
   a {
     display: inline-block;
     color: $darker-text-color;

app/javascript/flavours/glitch/styles/mastodon-light/diff.scss

@@ -585,3 +585,7 @@ a.sparkline {
     opacity: 0.25;
   }
 }
+
+kbd {
+  background-color: color.change($ui-highlight-color, $alpha: 0.1);
+}