FastAPI authentication and user updates

[erikguntner]

What changes did you make?

• Restructured a few endpoint paths
• Added the sign up confirmation route
• Added sign out route
• Fixed issue with refresh flow using the wrong value for secret hash
• Added delete user route to users controller
• Updated frontend services and query hooks to work with new endpoints
• Updated loading state on signup and sign in forms to use single variable
• Removed google auth buttons from sign up and sign in until we migrate to Hack for LA account

  Testing done for these changes

• Manual testing of endpoints and going through the sign up, sign in, sign out, and forgot password flows.