Apply ArgumentNullException.ThrowIfNull to NLog source-code

[snakefoot]

Has been introduced with NET6, but it should be "easy" to implement equal solution in NLog.Internal:

From:

            if (factory is null)
            {
                throw new ArgumentNullException(nameof(factory));
            }

To

           ArgumentNullException.ThrowIfNull(factory);

From:

            _logger = logger ?? throw new ArgumentNullException(nameof(logger));

To:

           _logger = ArgumentNullException.ThrowIfNull(logger);

https://docs.microsoft.com/en-us/dotnet/api/system.argumentnullexception.throwifnull?view=net-6.0

Ex.

static internal class ArgumentNullException
{
    public static T ThrowIfNull<T>(T argument, [CallerArgumentExpression("argument")] string paramName = null)
        where T : class
    {
        if (argument is null)
        {
            throw new System.ArgumentNullException(paramName);
        }

        return argument;
    }
}