Fix username case

What does this MR do and why?

This lowers all user input for user creation usernames. This is important because when we take username input from the login screen we lower it so logins are no longer case sensitive. This is breaking if a user is able to create a username with a capital. Then they cannot login.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• Have you checked this doesn't interfere/conflict/duplicate someone elses work?
• Have you fully tested your changes?
• Have you resolved any lint issues?
• Have you assigned a reviewer?
• Have you applied correct labels?