Users management: Update user details screen #7720776

Proposed Changes

• Update copy
• Team member edit form: Added title to match the User Details design
• Introduced autosave functionality on team member edit form

Testing Instructions

• Go to /people/team-members/{SITE_SLUG}
• Click on the team member item
• Try to edit the role or toggle the contractor checkbox
• Check if autosave works

Known issues:

• Updating the admin profile shows “There was an error updating…” but the change is saved (the same behavior is on production so it is not introduced with this PR)

Screenshots

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• Have you written new tests for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the “[Status] String Freeze” label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
• For changes affecting Jetpack: Have we added the “[Status] Needs Privacy Updates” label if this pull request changes what data or activity we track or use (p4TIVU-ajp-p2)?

Related to #71718