Supabase fixed, navbar/login/logout working.

I fixed the issue with the supabase component. All I had to do was read until the end of the issues thread, the fix was just a few lines.

Next up, I will make the navbar display the username and login/logout buttons depending on whether the user is logged in.

I can now log in and log out using the navbar and it's displayed on the tutorials page.

Next up, I need to make the login and signup page pretty, as the style is messed up, and add a courses page.