In-client signup form

Currently, new residents are directed to an external web browser to complete signup. Let's move signup into the in-viewer browser when a user clicks "Create account" from the viewer.

UX design is here: https://drive.google.com/file/d/1mXq_QThse5Fgad6fE48MnmQfzTeK7lcS/view?usp=drive_link

After the account is created, either pass the credentials to the viewer to pre-fill in the form, or (even more desirable) automatically log the user in.

Future expansion:

• Detect first login this install and display the create account flow instead of splash screen automatically.

We can assume that the web based Join flow will handle in-viewer registration in any special way necessary, similar to modifications made for mobile and P0.

Test Plan

• Verify that a user can sign up for a new account entirely within the client, without launching an external browser
• Ensure all necessary account creation fields and privacy disclosures are presented in the client sign-up UI
• Confirm that new accounts created via the client function correctly and receive appropriate initial content/experiences
• Test this workflow across multiple platforms (Windows, Mac, etc.)
• Validate security and privacy of user data throughout the process
• Validate passing of credentials to the viewer (or directly to login)