HttpClient support for specifying local end point

### Background
WebRequest class has been [deprecated](https://github.com/dotnet/platform-compat/blob/master/docs/DE0003.md).
Deprecation recommendation is to use .Net HttpClient and third party FTP client instead.

### Problem
WebRequest supports setting local end point with ServicePoint.BindIPEndPointDelegate.
The suggest third party FTP client support setting local IP end point but
.Net HttpClient can not replace HttpWebRequest because it does not support setting local IP end point.

### Solution
Add support for setting local IP end point for HttpClient or
add a list of third party HTTP clients support setting local IP end point to the deprecation recommendation.