updated avatar component name, added ability to change username (only works server side for now), updated signin page, updated Footer

Still working on the account settings page but didn't want to get behind on commits.

website/src/middleware.ts

@@ -4,5 +4,5 @@ export { default } from "next-auth/middleware";
  * Guards all pages under `/grading` and redirects them to the sign in page.
  */
 export const config = {
-  matcher: ["/grading/:path*"],
+  matcher: ["/grading/:path*", "/account/:path*", "/summarize/:path*"],
 };