Feature Request/Idea: Account Sign Up for Builtin Users

Overview of the Feature Request
We need to support account creation for built in users in the Modern UI, similar to the JSF UI sign up form. In addition, we want to give the users the ability to add an ORCID id and a ROR.

For security reasons, we don't want an to expose an API for account creation, instead, we need an API for provisioning a user account, and have a separate process for validating the user's email, and creating the user account after email validation.

An option for email verification is to use Keycloak, but that would require us to update our Keycloak SPI to handle storing the user accounts in Dataverse. (Currently the SPI is used for authenticating users, not creating them)

What kind of user is the feature intended for?
(Example users roles: API User, Curator, Depositor, Guest, Superuser, Sysadmin)

What inspired the request?
SPA Production Rollout; Supporting ROR and ORCID metadata

What existing behavior do you want changed?
Account Sign Up for builtin users

Any brand-new behavior do you want to add to Dataverse?
We want to be able to save the user's ORCID and ROR at the time of sign up.

Any open or closed issues related to this feature request?
https://github.com/IQSS/dataverse-frontend/issues/1021
https://github.com/IQSS/dataverse-frontend/issues/1022

Start by reviewing the linked dataverse-frontend issues 1021 and 1022, then compare the requested Modern UI flow with the existing JSF sign-up form. Define how provisioning, email validation, Keycloak integration, and ORCID/ROR storage should fit together; done requires an agreed account-creation flow rather than only a form.