[keycloak-dev] Reset admin password

We need a way to reset the admin password in case it is lost or hijacked. The proposal is to do that through an operation on the keycloak-server-subsystem that only runs in "offline CLI" mode. First, we currently allow you to delete the admin user. Should we disallow that and make the master admin user permanent? Should the new operation only work on the master admin password or can it be applied to any user in any realm?