plugin for drain decisions

Describe the feature
when deciding if a node should be terminates (for example for scheduled maintainance) we want to say "don't do it now if the cluster is in trouble" by for example looking at the current node health (tainted / notread / custom node statuses) across the cluster.

Is the feature request related to a problem?
No

Describe alternatives you've considered
Built-in logic would not work since these decisions could be very custom.

未指定文件、测试或入口点。首先定位负责做出 node drain 或终止决策的代码，并确定 plugin 如何检查整个 cluster 的 node 健康状况；当自定义逻辑能够在 cluster 不健康时否决 drain，且无需硬编码某一种健康策略时，即视为完成。