Refactor BeerPostHeader, refactor login and register

- Updated BeerPostHeader in /id page to use semantic HTML tags
- Removed the getServerSidesProps fn in /login and /register. Moved the redirect logic over to the client, will redirect on the client side.
- Added delete BeerPost option on the edit page.

hooks/useRedirectIfLoggedIn.ts

@@ -0,0 +1,17 @@
+import UserContext from '@/contexts/userContext';
+import { useRouter } from 'next/router';
+import { useContext, useEffect } from 'react';
+
+const useRedirectWhenLoggedIn = () => {
+  const { user } = useContext(UserContext);
+  const router = useRouter();
+
+  useEffect(() => {
+    if (!user) {
+      return;
+    }
+    router.push('/');
+  }, [user, router]);
+};
+
+export default useRedirectWhenLoggedIn;