PlayerMessageLevel Property

Keep in sync with MediaLogMessageLevel We are currently keeping the message level 'error' separate from the PlayerError type because right now they represent different things, this one being a DVLOG(ERROR) style log message that gets printed based on what log level is selected in the UI, and the other is a representation of a media::PipelineStatus object. Soon however we're going to be moving away from using PipelineStatus for errors and introducing a new error type which should hopefully let us integrate the error log level into the PlayerError type.

public string Level { get; set; }

public:
property String^ Level {
	String^ get ();
	void set (String^ value);
}