Implement scripting framework/API (.NET)

This is required in order to interact with the server from .NET side. API would have to be introduced.

For example to kick a specific player from the server, one way would be to have a managed class representing player/client.
```cs
// Find the target player
var ply = Player.GetByID(8);
// Kick the player
ply?.Kick(/*reason*/);
```