feat: expose resources over HTTP

[pemrouz]

Ripple resources are based on REST, so it should be fairly easy to enable serving them over HTTP. A request-response would simply be a strict subset of the realtime behaviour and just return a snapshot in time.

The HTTP request just needs to be translated to a request object (e.g. verb -> type, URL -> name, body -> value) and then passed to the existing resource handlers. The generic actions/mutations in use are (each of which can be an arbitrarily deep operation by specifying a key):

{ type: 'add', key: 'a.b.c', value }
{ type: 'update', key: 'a.b.c', value }
{ type: 'remove', key: 'a.b.c' }

Acceptable HTTP requests would be:

• GET is a pull but without setting up a subscription.
• PUT is an update at the root of the resource (i.e. with no key specified).
• DELETE is a remove at the root of the resource (i.e. with no key specified).
• POST/PATCH can just accept any change object as the body.

This would be useful for interoperability with existing tools like curl, or allowing developers to use fetch if desired.

Bonus: We can also auto-generate perfect hypermedia API with links by checking the media-type (e.g. application/hal+json) and returning the correct format with the link information.