Implement validation of the player identity against the IDP

[thoraxe]

Ultimately the player identity is stored in RHSSO. In order for a player to access the client, they'll need to be authenticated to RHSSO. When the player joins the server, they'll be transmitting their identity in some way, and the server should probably validate who they say they are.

A quick search turned up this library:
https://github.com/Thalhammer/jwt-cpp

This would allow us to have the client send a JWT to the server, and the server could then validate that JWT against RHSSO?