Fix ItemSeparatorComponent's leadingItem prop not being updated

[brunolemos]

Summary

Fix #24592

Just added a getDerivedStateFromProps, similar to what VirtualizedSectionList already does:

react-native/Libraries/Lists/VirtualizedSectionList.js

Lines 470 to 492 in 18feded

	static getDerivedStateFromProps(
	props: ItemWithSeparatorProps,
	prevState: ItemWithSeparatorState,
	): ?ItemWithSeparatorState {
	return {
	separatorProps: {
	...prevState.separatorProps,
	leadingItem: props.item,
	leadingSection: props.leadingSection,
	section: props.section,
	trailingItem: props.trailingItem,
	trailingSection: props.trailingSection,
	},
	leadingSeparatorProps: {
	...prevState.leadingSeparatorProps,
	leadingItem: props.leadingItem,
	leadingSection: props.leadingSection,
	section: props.section,
	trailingItem: props.item,
	trailingSection: props.trailingSection,
	},
	};
	}

Changelog

[General] [Fixed] - Fix ItemSeparatorComponent's leadingItem prop not being updated

Test Plan

Tested on my app.
Reproduction code: https://snack.expo.io/@brunolemos/itemseparatorcomponent-bug

[cpojer]

Thank you!

[facebook-github-bot]

@cpojer is landing this pull request. If you are a Facebook employee, you can view this diff on Phabricator.

[react-native-bot]

This pull request was successfully merged by @brunolemos in 1e42809.

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