updated plasmic package to work with new hooks + added example

examples/plasmic/src/pages/plasmic-host.tsx

@@ -0,0 +1,7 @@
+import * as React from 'react';
+import { PlasmicCanvasHost } from '@plasmicapp/loader-nextjs';
+import { PLASMIC } from '@/plasmic-init';
+
+export default function PlasmicHost() {
+   return PLASMIC && <PlasmicCanvasHost />;
+}