java11 client should consider Options::connectTimeoutMillis

[gb-klein]

feign.http2client.Http2Client seems not to consider Options::connectTimeoutMillis. In the course of #1233 request timeout was fixed - but not the connect timeout.

Implementation note: this would have to be set on the HttpClient instance (e.g. via Builder::connectTimeout). One could do this manually by providing a custom built HttpClient to Http2Client. However it would be good to leave this over to Http2Client when it constructs the HttpClient for us. E.g. by replacing the default constructor with a constructor taking Options or (IMHO better) lazily instantiating HttpClient - if no custom was specified via constructor - when the request should be sent.

[ChunMengLu]

Yes, it is more complicated to implement.

I think it is enough to customize connectTimeoutMillis in most scenarios on HttpClient.