Makes it possible to change the HTTP client

[niucho]

Add provider for collect prometheus metric of http client

This is sample

	lksdk.DefaultHttpClientProvider.NewHttpClient = func(name string) *http.Client {
		return &http.Client{Transport: instrumentRoundTripper(reg, name, http.DefaultTransport)}
	}
        // need to copy method instrumentRoundTripper from https://github.com/prometheus/client_golang/blob/main/tutorial/whatsup/reference/main.go#L283-L319