DDLS-402 - Migrate existing data from dd_user table to deputy table

[Raffers]

Purpose

Allows us to separate account information from deputy entity and move one step closer to aligning Lay deputy data to Prof and PA.

Fixes DDLS-402

Approach

This PR changes data type, required before migration script can be committed.

Learning

Any tips and tricks, blog posts or tools which helped you. Plus anything notable you've discovered about DigiDeps

Checklist

• I have performed a self-review of my own code
• I have updated documentation (Confluence/ADR/tech debt doc) where relevant
• I have added tests to prove my work
• The product team have approved these changes
• I have checked my work for potential security issues and refered to the OWASP top 10

Frontend

• I have run an in-browser accessibility test (e.g. WAVE, Lighthouse)
• There are no deprecated CSS classes noted in the profiler
• Translations are used and the profiler doesn't identify any missing
• Any links or buttons added are screen reader friendly and contextually complete
• If adding GA events, I have updated or checked the existing category or label values