Update Fauna examples to support new FAUNA_DB_DOMAIN environment variable

[trevor-fauna]

Documentation / Examples

• [] Make sure the linting passes by running pnpm lint
• The examples guidelines are followed from our contributing doc

[balazsorban44]

Maybe this example should be deprecated in favor of with-fauna: https://github.com/vercel/next.js/tree/canary/examples/with-fauna

[trevor-fauna]

Maybe this example should be deprecated in favor of with-fauna: https://github.com/vercel/next.js/tree/canary/examples/with-fauna

I'd consider that outside of the scope of this change, which is just to bring the current examples up to parity. That said, the cookie example is slightly different as it's accepting the authN/authZ context from an upstream request and passing that along, whereas with-fauna just has it baked into the deployed infra.

[ijjk]

Thanks!