refactor: add login response validation

[Prithpal-Sooriya]

Explanation

Profile Syncing. Adds login response validation from the developer/users storage medium.
The user could lie and pass in an invalid login response, so this makes sure that there is some validation around the response shape.

NOTE - we can improve this in the future by adding a runtime parser/validator like Zod. But this is out of scope and we can add in a separate PR.

References

NOTIFY-881

Changelog

@metamask/profile-sync-controller

• ADDED: Validation around the LoginResponse shape.

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've highlighted breaking changes using the "BREAKING" category above as appropriate

[mathieuartu]

Nice!