Add /swagger.json endpoint to provide specfile

[winder]

Similar to the go-algorand repo, we should provide an endpoint for fetching the open api specfile.

Unlike the old swagger.json endpoint, the v2 endpoints are split into multiple pieces. We need to find a way to merge them together.

[ryanRfox]

I'm currently drafting the SDK guides on the Developer Portal as
curl http://{host:port}/swagger.json

I'd appreciate some feedback on anticipated implementation, priority, roadmap for this.

[scholtz]

any progress?