When opening plex Oauth window, open an empty page then redirect to plex oauth (#127)

* feat(frontend): custom toast

* refactor(frontend): move toast width styling to globals

* feat(frontend): add loading spinner for browser popup

src/pages/login/plex/loading.tsx

@@ -0,0 +1,12 @@
+import React from 'react';
+import LoadingSpinner from '../../../components/Common/LoadingSpinner';
+
+const PlexLoading: React.FC = () => {
+  return (
+    <div>
+      <LoadingSpinner />
+    </div>
+  );
+};
+
+export default PlexLoading;