chore: helper methods to extract user data from req (#5710)

With the recent changes it's common that we'll need both the id and
processed username from the auth user in the request, so this PR
provides some helper methods to simplify this.

src/lib/util/extract-user.ts

@@ -7,3 +7,10 @@ export function extractUsernameFromUser(user: IUser): string {
 export function extractUsername(req: IAuthRequest): string {
     return extractUsernameFromUser(req.user);
 }
+
+export const extractUserId = (req: IAuthRequest) => req.user.id;
+
+export const extractUserInfo = (req: IAuthRequest) => ({
+    id: extractUserId(req),
+    username: extractUsername(req),
+});