Add Express.js boilerplate and consistent error handling middleware

Changes:
- Convert router.ts to app.ts and routers/auth-router.ts to separate routers from Express.js app
- Remove signal listeners as they do not work for the Jami daemon
- Add 'error' and 'listening' event listeners to the HTTP server to show useful info on startup
- Add error handling middleware to return error strings rather than HTML

Change-Id: Icc0410a9fc596a419be024c6b0503ca4183f7563
diff --git a/server/src/app.ts b/server/src/app.ts
new file mode 100644
index 0000000..f126ed4
--- /dev/null
+++ b/server/src/app.ts
@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2022 Savoir-faire Linux Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation; either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public
+ * License along with this program.  If not, see
+ * <https://www.gnu.org/licenses/>.
+ */
+import express, { NextFunction, Request, Response } from 'express';
+import log from 'loglevel';
+import { Service } from 'typedi';
+
+import { StatusCode } from './constants.js';
+import { AuthRouter } from './routers/auth-router.js';
+
+@Service()
+class App {
+  constructor(private authRouter: AuthRouter) {}
+
+  async build() {
+    const app = express();
+
+    // Setup routing
+    const authRouter = await this.authRouter.build();
+    app.use('/auth', authRouter);
+
+    // Setup 404 error handling
+    app.use((_req, res) => {
+      res.sendStatus(StatusCode.NOT_FOUND);
+    });
+
+    // Setup internal error handling
+    app.use((err: Error, _req: Request, res: Response, _next: NextFunction) => {
+      log.error(err);
+      res.status(StatusCode.INTERNAL_SERVER_ERROR).send(err.message);
+    });
+
+    return app;
+  }
+}
+
+export { App };