Allow applying middleware before know about request uri and methods

[iEricKoh]

Currently the middleware function is under Request.

I am trying to create and reuse a client, a sign will be calculated base on the url path and query.
Is it possible that I can create a http client with applied middleware before know about any uri and http methods?

Basically it's request/response interceptor.

for example:

let client = surf::Client::new();
let client = client.middleware(...)  // no middleware func exist in the client

let request = Request { client }

// the middleware func will be executed before sending out the request
request.client.get("https://httpbin.org/get").recv_string(); 

[yoshuawuyts]

@iEricKoh hi, thanks for filing! Yeah this is something we should be supporting. We've recently be adding a sibling of this functionality into Tide through http-rs/tide#379.

Marking this as something we should add.

[Fishrock123]

#192 also proposes moving the middleware onto the Client like this.