Improvements

• #6027 FileTarget - Improve archive cleanup when using ArchiveSuffixFormat with datetime. (@snakefoot)
• #6028 FileTarget - Fix archive cleanup when only single old file and using MaxArchiveDays. (@snakefoot)
• #6039 FileTarget - Render ArchiveSuffixFormat using NLog DefaultCultureInfo. (@snakefoot)
• #6030 ObjectReflectionCache - Improve handling of JObject serialization. (@snakefoot)
• #6026 JsonLayout - Reduce code complexity for rendering JsonAttribute. (@snakefoot)
• #6036 NullTarget - Improve thread concurrency when FormatMessage = false. (@snakefoot)
• #6023 MemoryTarget - Apply MaxLogsCount limit on next LogEvent. (@snakefoot)
• #6040 XmlParser - Refactor to reduce code complexity. (@snakefoot)
• #6041 ScopeContextAsyncState - Refactor to reduce code complexity. (@snakefoot)