Chore: Update with-supabase example to Next.js 16 (#86105)
### What?
Upgrade with-supabase example to be compatible with Next.js 16
### Why?
1. Users get console warnings about middleware vs proxy
2. Enabling Cache Components config results in build errors for async
behaviour outside Suspense boundary
3. Turbopack flag is default and therefore, no longer necessary on `npm
run dev`
### How?
1. Renamed all instances of `middleware` to `proxy`
2. Wraped async behaviour in Suspense boundaries
3. Removed --turbopack flag from `npm run dev`
---------
Co-authored-by: JJ Kasper <jj@jjsweb.site>
