Create Serilog Enricher to add Request header in logs

## CorrelationIdEnricher.cs
    public class CorrelationIdEnricher : ILogEventEnricher
    {
        public void Enrich(LogEvent logEvent, ILogEventPropertyFactory propertyFactory)
        {
            if (logEvent == null) throw new ArgumentNullException("logEvent");

            if (HttpContext.Current == null)
                return;

            if (HttpContext.Current.Request == null)
                return;

            string correlationId = HttpContext.Current.Request.Headers["CorrelationId"];

            if (string.IsNullOrWhiteSpace(correlationId))
                return;

            var correlationIdProperty = new LogEventProperty("CorrelationId", new ScalarValue(correlationId));
            logEvent.AddPropertyIfAbsent(correlationIdProperty);
        }
    }