关于KeepAlive组件

[https://github.com/baidu/san/issues/780](url)

在上面那个issue中有一个思路，但是这个思路只是保持了状态，而每次还是会执行生命周期方法，比如 attached 等，这样就导致每次切换选项卡的时候组件还是会调用后端api获取数据并渲染，这样体验不是很好，尤其是后端响应不是很快的场景下体验更差，官方是否可以考虑出一个这样的组件呀？现在很需要这个功能，我看以前的issue中也有人提过的呀，谢谢！

Start by reading issue #780 and the discussion about preserving component state during tab switches. Clarify the expected KeepAlive lifecycle behavior and define done as switching tabs without rerunning lifecycle methods or refetching and rerendering data unnecessarily.

Written by the indexing model from the issue text.