Start save role in both users and user_details table

What does this MR do and why?

We added a new field for role in user_details.onboarding_status jsonb column, this MR saves role to the new field while keeps saving it to users table. Later we will backfill user_details.onboarding_status with existing user.role data and eventually drops user.role.

References

Please include cross links to any resources that are relevant to this MR. This will give reviewers and future readers helpful context to give an efficient review of the changes introduced.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

No change.

How to set up and validate locally

1. Register a new user through /users/sign_up
2. Verify in rails console the new user has role and onboarding_status_role.

Related to #498739 (closed)