Add migrated to .NET 8.0 variant of Hcs.Client

Hcs.ClientNet/GostXades/Helpers/DateTimeHelper.cs

@@ -0,0 +1,14 @@
+using System;
+
+namespace GostXades.Helpers
+{
+    public static class DateTimeHelper
+    {
+        public static DateTimeOffset ToDateTimeOffset(this DateTime dateTime, int timeZoneOffsetMinutes = 0)
+        {
+            var shiftedDateTime = dateTime.AddMinutes(timeZoneOffsetMinutes);
+            var unspecifiedDateTime = DateTime.SpecifyKind(shiftedDateTime, DateTimeKind.Unspecified);
+            return new DateTimeOffset(unspecifiedDateTime, new TimeSpan(0, timeZoneOffsetMinutes, 0));
+        }
+    }
+}