Add required action for phone validation

[melegiul]

• [x] Add required action for phone validation
• [x] Implement SMS code validation for this action
• [x] Add option to force users to setup 2FA with SMS auth https://github.com/netzbegruenung/keycloak-2fa-sms-authenticator/pull/20/commits/04d640b2d8b8a033055bf5603aad7d604f4b14fd
• [ ] ~Cleaner solution for loading auth configs~ moved to #24

After phone number submission, the phone is stored in AuthenticationSessionModel and a PhoneValidationRequiredAction is triggered. Phone validation sends SMS code and finally stores users phone number after valid SMS code submission.

TODOs ~When the SMS code validation is aborted without valid code submission, the PhoneNumberRequiredAction is considered as "successful" despite of SMS Authentication could not be setup due to the missing SMS code. In this case PhoneNumberRequiredAction should be considered as failed.~

Fixes: #16 Fixes: #22 Fixes: #23

[svenseeberg]

Potential solution: at the beginning of step 2 create another required action for step 1. If step 2 is successful, delete the required action for step 1.

[svenseeberg]

@melegiul I'd suggest to merge as is and create a new issue for the static Config Alias. I already updated the README in the main branch accordingly.