[BUG] Render emojis in labels in issue info popup

- Currently emojis that are part of the label's name aren't rendered
when shown in the popup that you get when you hover over issue
references.
- This patch fixes that by rendering the emoji.
- Adds CSS to not make the emoji big in the label.
- Resolves #1531

web_src/css/repo.css

@@ -3010,3 +3010,7 @@ tbody.commit-list {
   margin-top: -1px;
   border-top: 1px solid var(--color-secondary);
 }
+#issue-info-popup .emoji {
+  font-size: inherit;
+  line-height: inherit;
+}