[FEATURE] Support DurableObjects

[mattboardman]

Is your feature request related to a problem?

Currently the documentation suggests using another worker for RPC services and DurableObjects. link

There isn't a documented way to bring the DurableObject into the same worker of a nextjs service.

Describe the solution you'd like

Ideally we can add/import DurableObject classes to an index.ts file in the src/ directory and have those made available in the bundle's worker.js file upon build. This would reduce the need for multiple workers to host a nextjs site with access to DO's. I imagine there would also be performance and latency gains as well (but I don't know enough about the RPC protocol to make that claim for sure).

Describe alternatives you've considered

The alternative right now is to build multiple workers and delegate RPC Services and DurableObject code to those workers.

@opennextjs/cloudflare version

0.3.0

Additional context

No response

Before submitting

• I have checked that there isn't already a similar feature request
• This is a single feature (not multiple features in one request)

[Fawwaz-2009]

I saw that this is under the documentation column in the roadmap, does this mean we can actually already do this but it's not documented yet?

[timReynolds]

Given the recently release of agents-sdk using durable objects this would be a great additional feature making integrating an agent into next using Cloudflare simpler

[tomocrafter]

Why this issue is on status of documentation? Is function to support durable object with open-next supported but not doucmented?
I read source code for a hour but I don't think it is supported.

[vicb]

See #591