修复 生成Snowflake ID为负数的问题

[SxxSolar]

更新 IdUtil.SnowflakeId()

/// <summary>
/// 生成Snowflake ID
/// </summary>
/// <returns>生成的Snowflake ID</returns>
public static long SnowflakeId()
{
	lock (lockObj)
	{
		long timestamp = DateTime.UtcNow.Ticks - epochTicks;

		if (timestamp < lastTimestamp)
		{
			throw new Exception("时钟向后移动，拒绝生成Snowflake ID");
		}

		if (timestamp == lastTimestamp)
		{
			sequence = (sequence + 1) & sequenceMask;

			if (sequence == 0)
			{
				timestamp = NextMillis(lastTimestamp);
			}
		}
		else
		{
			sequence = 0L;
		}

		lastTimestamp = timestamp;

		return ((timestamp << (int)(workerIdBits + sequenceBits)) |
		   (datacenterId << (int)sequenceBits) |
		   (workerId << (int)sequenceBits) |
		   sequence) & long.MaxValue; // 添加 & long.MaxValue
	}
}

修复 生成Snowflake ID为负数的问题
添加测试方法