Optimize NLogLogger

[snakefoot]

Add this as property to the NLogLogger-class (Use Log instead of constantly calling GetCurrentClassLogger) :

private ILogger Log { get { return _log ?? (_log = LogManager.GetCurrentClassLogger()); } }
ILogger _log;

Improve the following method:

das-shared-packages/Logging/Logger/SFA.DAS.NLog.Logger/NLogLogger.cs

Lines 185 to 187 in d1a0f36

	private void SendLog(object message, LogLevel level, IDictionary<string, object> properties, Exception exception = null)
	{
	var propertiesLocal = properties ?? new Dictionary<string, object>();

By adding IsEnabled-check to the beginning of the SendLog-method above:

    if (!Log.IsEnabled(level))
        return;   
  
   var propertiesLocal = properties ?? new Dictionary<string, object>(); 

Introduce this new SendLog method with the following parameters (And fix all Log-methods that calls BuildProperties to instead pass ILogEntry to this new method):

void SendLog(object message, LogLevel level, ILogEntry logEntry, Exception exception = null)
{
    if (!Log.IsEnabled(level))
        return;

    SendLog(message, level, BuildProperties(logEntry), exception);
}

Modify the this SendLog-method:

das-shared-packages/Logging/Logger/SFA.DAS.NLog.Logger/NLogLogger.cs

Lines 140 to 142 in d1a0f36

	private void SendLog(object message, LogLevel level, Exception exception = null)
	{
	SendLog(message, level, new Dictionary<string, object>(), exception);

So it becomes:

void SendLog(object message, LogLevel level, Exception exception = null)
{
    if (!Log.IsEnabled(level))
        return;

    SendLog(message, level, new Dictionary<string, object>(), exception);
}

[snakefoot]

@leewadhams This will minimize the cost of logging and optimize performance.