[Feature Request]: Websocket Support

[juzeon]

Describe the feature / enhancement and how it would improve things

Hello. Thanks for the library!

I'm not sure how it can work with Websocket. Typically I use this library, which requires a http client:

connRaw, resp, err := websocket.Dial(ctx,
	o.wssURL,
	&websocket.DialOptions{
		HTTPClient: client,// a *http.Client instance, not a tlsclient.HttpClient
		HTTPHeader: httpHeaders,
	})

Describe how your proposal will work, with code and/or pseudo-code

I have tried to implement a fake RoundTripper by:

// ...omit...
func (s MyRoundTripper) RoundTrip(hReq *http.Request) (*http.Response, error) {
	fReq, err := fhttp.NewRequest(hReq.Method, hReq.URL.String(), hReq.Body)
	if err != nil {
		return nil, err
	}
	fReq.Header = fhttp.Header(hReq.Header)
	fReq.Trailer = fhttp.Header(hReq.Trailer)
	fReq.Form = hReq.Form
	fReq.MultipartForm = hReq.MultipartForm
	fReq.PostForm = hReq.PostForm

	fResp, err := s.Client.Do(fReq)// s.Client is a tlsclient.HttpClient
	if err != nil {
		return nil, fmt.Errorf("error fetching response: %w", err)
	}
	return &http.Response{
		Status:           fResp.Status,
		StatusCode:       fResp.StatusCode,
		Proto:            fResp.Proto,
		ProtoMajor:       fResp.ProtoMajor,
		ProtoMinor:       fResp.ProtoMinor,
		Header:           http.Header(fResp.Header),
		Body:             fResp.Body,
		ContentLength:    fResp.ContentLength,
		TransferEncoding: fResp.TransferEncoding,
		Close:            fResp.Close,
		Uncompressed:     fResp.Uncompressed,
		Trailer:          http.Header(fResp.Trailer),
		Request:          hReq,
		TLS:              nil,
	}, nil
}

And use like this:

client := &http.Client{}
client.Transport = &MyRoundTripper{...omit initializing here...}
connRaw, resp, err := websocket.Dial(ctx,
	o.wssURL,
	&websocket.DialOptions{
		HTTPClient: client,// a *http.Client here
		HTTPHeader: httpHeaders,
	})

But I got this:

"failed to WebSocket dial: failed to send handshake request: Get \"https://...omit...": http2: invalid Upgrade request header: [\"websocket\"]"

Thanks in advance!