[Feature Request] LoadMore可否提供一个记录滚动位置的功能(can not remeber the position of the scrollbar)

### Existing Component
是

### Component Name
loadmore

### Description
当我从列表页面进入详情页面的时候，我需要缓存列表页面，当回到列表页面时，页面虽然缓存了，但是列表又滚动到了顶部。所以希望可以增加一个滚动的回调返回滚动位置，列表太长的时候可以回到之前滚动的位置

Start with the loadmore component and trace how it handles scrolling when a list is cached and revisited. Define the callback's position data and verify that a consumer can use it to return to the prior scroll position; the issue does not name a file or test to run.

Written by the indexing model from the issue text.