Implement initial access token

[yarons]

Apparently Keycloak has a builtin support for initial token, now we need to find a way to generate those tokens on the Kibbutz systems either by using some SP or with a dedicated service that encodes these kind of tokens.

https://github.com/keycloak/keycloak-documentation/blob/main/securing_apps/topics/client-registration.adoc

[yarons]

Another explanation, we should script that and send it automagically when a new number is being added to the system, the only thing missing is: How can this token reflect NPP status?

https://stackoverflow.com/questions/58988651/how-to-get-initial-access-token-from-keycloak-client-registration-using-rest-api