Summary:
Currently `ListHeaderComponent` & `ListFooterComponent` allow to use React Componetn & Elemelen
```tsx
<FlatList
ListHeaderComponent={<View />} // valid
ListHeaderComponent={View} // valid
/>
```
But when you try to pass `ItemSeparatorComponent` as React Element it will throw an error
```tsx
<FlatList
ItemSeparatorComponent={View} // ok
ItemSeparatorComponent={<View />} /* not valid:
Error: Element type is invalid: expected a string (for built-in components) or a class/function
(for composite components) but got: object.
Check the render method of `CellRenderer`.
*/
/>
```
So, this PR adds this ability
## Changelog
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https://github.com/facebook/react-native/wiki/Changelog
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[General] [Changed] - Add ability to pass `ItemSeparatorComponent` as React Element
Pull Request resolved: https://github.com/facebook/react-native/pull/32748
Test Plan: ...
Reviewed By: lyahdav
Differential Revision: D37227719
Pulled By: cortinico
fbshipit-source-id: 1c4943fa9d42bf5e61fbd999d1f5be46b51ecb14