Application initialization events (#3680)

* Adds `not_found` hook

* Separate hooks and endpoints initialization process

* Adds additional application events

* Remove unused import

* Change the event order to accound for notFound and errorHandler

* Change emitAsync.catch to use the emitAsyncSafe function

* Updated docs, reordered table by lifecycle and usage

api/src/controllers/not-found.ts

@@ -1,8 +1,29 @@
 import { RequestHandler } from 'express';
 import { RouteNotFoundException } from '../exceptions';
 
-const notFound: RequestHandler = (req, res, next) => {
-	throw new RouteNotFoundException(req.path);
+import emitter from '../emitter';
+
+/**
+ * Handles not found routes.
+ *
+ * - If a hook throws an error, the error gets forwarded to the error handler.
+ * - If a hook returns true, the handler assumes the response has been
+ *   processed and won't generate a response.
+ *
+ * @param req
+ * @param res
+ * @param next
+ */
+const notFound: RequestHandler = async (req, res, next) => {
+	try {
+		const ret = await emitter.emitAsync('request.not_found', req, res);
+		if (ret.reduce((prev, current) => current || prev, false)) {
+			return next();
+		}
+		next(new RouteNotFoundException(req.path));
+	} catch (err) {
+		next(err);
+	}
 };
 
 export default notFound;