Add FCH

[a-thieme]

No description provided.

[Copilot]

Pull Request Overview

This PR adds a new FCH client for the NDN-FCH service, enabling HTTP queries to retrieve router information.

• Introduces core types (Request, Response, Router) with helper functions to apply defaults and build query URLs.
• Implements the Query function to perform HTTP requests and parse responses into routers.

Files not reviewed (1)

• go.mod: Language not supported

Comments suppressed due to low confidence (1)

std/ndn/fch/fch.go:47

• The function 'max' is referenced here but is not defined. Consider defining a helper function or using appropriate logic to ensure req.Count is at least 1.

req.Count = max(1, req.Count)

[zjkmxy]

Tested with the following code and it works.

res, err := fch.Query(context.Background(), fch.Request{})
if err != nil {
	println(err)
} else {
	retJson, _ := json.Marshal(res)
	println(string(retJson))
}

[a-thieme]

we'll probably want to squash the commits during the merge to main

[zjkmxy]

LGTM