Add github webhook and mapping

src/utils/github-user-utils.ts

@@ -0,0 +1,13 @@
+import { Database } from '../shared/Database';
+
+const mentionRegex = new RegExp('@([\\S]+)', 'gi');
+
+export async function fixPings(body: string): Promise<string> {
+  const mappings = await Database.getAllGithubUserMappings();
+
+  return body.replaceAll(mentionRegex, (match, username) => {
+    const mapping = mappings.find(m => m.github_username == username);
+
+    return mapping ? `<@${mapping.discord_id}>` : match;
+  });
+}