NLogRequestLoggingModule - Introduce ShouldLogRequest

[snakefoot]

Like ShouldLogRequest is available for NLogRequestLoggingMiddleware, so one can downgrade LogLevel, then it should always be available for NLogRequestLoggingModule.

Maybe consider changing the logging so when LogLevel <= Info, then skip logging the exception. But just perform logging of the Exception.Type and Exception.Message (Ex. Input-Validation-Errors).

This could also be useful for ASP.NET Core, where HTTP 499 Client Closed Request together with TaskCanceledException should not be seen as "Error" (catch (OperationCanceledException) when (httpContext.RequestAborted.IsCancellationRequested))