[Membership] Implement a registration confirmation in the code

[dominikag2]

Motivation

Member that register on our site need to verify their email before their account is activated.
We need to implement an example of setting up an email service that will send a confirmation email to the new member after each registration.

The goal is to show our partners and customers a real-world example for XbyK.

Proposed solution

Enable email confirmation in our solution.
Implement new methods in the Registration controller to handle sending confirmation emails and handling both successful registration and errors the user can encounter.
Implement a static view to show email confirmation results to the user.