Restrict public reg

https://community.passbolt.com/t/as-an-admin-user-i-would-like-to-limit-sign-up-to-a-specified-domain/1140

This pull request is a (multiple allowed):

• [ ] bug fix
• [ ] change of existing behavior
• [x] new feature

Checklist

• [ ] User stories are present (given, when, then format)
• [x] Unit tests are passing
• [ ] Selenium tests are passing
• [x] Check style is not triggering new error or warning

What you did

Check for allowed_domains from config passbolt.registration.allowed_domains if public registration is allowed