Adding middleware-based authorization for Elysia controller endpoints

[MahmoudSheemy127]

In this PR, the authorization is slightly enhanced by introducing middleware-based authorization for the problems and groups controllers defined in Elysia.

Authorization is now handled through a defined common guard

.use(problemsModel)
	.use(isAuthenticated)  //Authorization middleware
	.get("/problems/today", async ({ user }) => {
		return problemsDao.getTodayForUser(user.id)
	})

This acts as a modular approach instead of writing the authorization logic manually inside each controller logic in a repitivie manner.

[husamql3]

Thanks @MahmoudSheemy127 for your contribution ❤️

As I already explained to you, the scope of this PR and its should be public. I'm assigning you another ticket so you can contribute with us 🚀