introduce a logout page and the navbar

src/components/logout.tsx

@@ -0,0 +1,22 @@
+import React, { useContext } from 'react';
+import { useNavigate } from 'react-router-dom';
+import { AuthContext } from '../contexts';
+
+export const Logout: React.FC = () => {
+  const context = useContext(AuthContext);
+  const navigate = useNavigate();
+
+  context.setAuth({
+    valid: false,
+    user: {
+      vatsimId: '',
+      fullName: '',
+      administrator: false,
+      airportConfigurationAccess: [],
+    },
+  });
+  sessionStorage.removeItem('token');
+  navigate('/');
+
+  return <></>;
+}