[FRONTEND] Group password login page

[hn275]

User will be redirected to this page if they are not yet authenticated an is trying to access a private group.

• It should have a warning/error state for when user entered the wrong password.
• Make it responsive.
• The process of hashing and comparing password takes a couple of seconds. It should have a loading state
• After authentication, user should be redirected to group page.
• Form validation: password length should be [8, 16] char, inclusive.

This ticket is only for the UI, no need to worry about connecting it to the backend.

[hn275]

@BenReichwein sir can I get a Figma for this at one point when you are free.