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

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MR acceptance checklist

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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