feat(auth): show "Last login" badge — GRO-1694

[RostiMelk]

Description

• Added "Last login" badge to Studio login screen
• Fixed footer logo to follow system theme (light mode / dark mode)

The "Last login" provider data is fetched from /users/me endpoint

What to review

• Make sure nothing breaks when user is not logged in to api.sanity.io
• Make sure provider badge is shown when user is logged in to api.sanity.io

Testing

Tbd

Notes for release

Tbd