feat: provide the request info in Context for all Storage() callbacks

[muir]

Is your feature request related to a problem? Please describe.

Several times I've needed information that is present in the original http.Request when implementing op.Storage APIs or even Client APIS.

Describe the solution you'd like

Capture the original http.Request and request body and put them into context.Context so any op.Storage API can get that information if it needs it.

Describe alternatives you've considered

Change all of the op.Storage APIs to include additional information.

[muhlemmer]

I'm not sure if we would want something like this, so I will take it up with my colleagues. Meanwhile. you could easily achieve this by creating your own middleware:

type ReqKeyT int

const ReqKey ReqKeyT = 0

func requestToCtx(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		ctx := context.WithValue(r.Context(), ReqKey, r)
		next.ServeHTTP(w, r.WithContext(ctx))
	})
}

	handler, err := op.NewOpenIDProvider(issuer, config, storage,
		//we must explicitly allow the use of the http issuer
		op.WithAllowInsecure(),
		// as an example on how to customize an endpoint this will change the authorization_endpoint from /authorize to /auth
		op.WithCustomAuthEndpoint(op.NewEndpoint("auth")),
		op.WithHttpInterceptors(requestToCtx),
	)

[muhlemmer]

Closing as this is the alternative solution to #326. Also discussed in discord.

[muir]

@muhlemmer There are other situations where the entire request is useful. In my implementation, I'm passing the request through to the storage layer (using Context) for /authorize, /revoke, and /end_session. We can solve those individually, but it seems like a general solution is warranted.