BOSH Support

[kimimaru4000]

Is your feature request related to a problem? Please describe.
I would like to request Artalk to support the BOSH (Bi-directional streams Over Synchronous HTTP) XMPP extension. Open Streaming Platform (OSP) uses XMPP/BOSH for its chat, and it would awesome to be able to connect a bot to it.

Specifically, I'd like to use Artalk for TRBot to connect to OSP, allowing for viewers to play games through the chat.

Describe the solution you'd like
Support for XMPP/BOSH in Artalk.Xmpp.

Describe alternatives you've considered
MatriX vNext is another .NET Standard library for XMPP, but documentation is lacking and the project looks abandoned.

Additional context
Here are examples of how TRBot works in practice. Viewers on OSP would be able to do the same if I can use Artalk in TRBot to connect to OSP chat.

Thank you very much for the awesome library, and I appreciate your time and consideration!