gnet client 支持连接池

[liujiangang01]

背景：连接池对于分布式系统（比较固定的ip和port）性能提升巨大

[github-actions]

This issue is marked as stale because it has been open for 30 days with no activity.

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[github-actions]

This issue was closed because it has been inactive for 7 days since being marked as stale.

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