improve repo/icon template, extract js function

web_src/js/utils/mappings.ts

@@ -0,0 +1,12 @@
+export function getRepoIcon(repo: Record<string, any>) {
+  if (repo.mirror) {
+    return 'octicon-mirror';
+  } else if (repo.fork) {
+    return 'octicon-repo-forked';
+  } else if (repo.private) {
+    return 'octicon-repo-locked';
+  } else if (repo.template) {
+    return `octicon-repo-template`;
+  }
+  return 'octicon-repo';
+}