Fix 403 scenario

[harminius]

Follow-up to #950, fixes the lost-access sceanrio reported in #935.

• When the server answers 403 on project info (the user's access was removed), @mm_project_role is now cleared instead of keeping the role from the last sync. This covers project switch and sign-in (refresh_project_role) and the Sync / status flow (project_status).
• Offline, server errors and an expired sign-in still keep the last synced role. An expired SSO token no longer raises a Python error on project switch, and no longer resets the client in create_manager.