Support fallback to Long Polling and Server Sent Events

[Sonic78]

Currently I couldn't find and documentation, readme etc. that describes if fallback to Long Polling and/or Server Sent Events are supported by this C++ client. Checking other tickets let me assume that currently the SignalR-Client-Cpp dosen't provide the essential fallback to Long Polling and/or Server Sent Events when WebSockets are not supported by the server or blocked by a firewall.
Please implement at least one fallback and somewhere document this limitation.

[moozzyk]

You are correct. Currently the only supported transport is websockets. This is tracked here: aspnet/SignalR-Client-Cpp#62 so I will close this issue as a duplicate.