Sub-task for #6307.

This issue is to track front end work for authenticating users as outlined in the above issue. Some states we should consider:

• Default login prompt when first accessing the UI
• Invalid username
• Invalid password
• Logging out once logged in

Including an early design from Kuan that was added in the above issue:

@josueeee as discussed, this will need some design attention. cc @vilterp and @couchand