fix(useElementHover): returns correctly hover state when element is removed

[ben-lau]

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⚠️ Slowing down new functions

Warning: Slowing down new functions

As the VueUse audience continues to grow, we have been inundated with an overwhelming number of feature requests and pull requests. As a result, maintaining the project has become increasingly challenging and has stretched our capacity to its limits. As such, in the near future, we may need to slow down our acceptance of new features and prioritize the stability and quality of existing functions. Please note that new features for VueUse may not be accepted at this time. If you have any new ideas, we suggest that you first incorporate them into your own codebase, iterate on them to suit your needs, and assess their generalizability. If you strongly believe that your ideas are beneficial to the community, you may submit a pull request along with your use cases, and we would be happy to review and discuss them. Thank you for your understanding.

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Description

closes #4379 , use mutationobserver to observe whether the element are removed.
By adding a new argument to avoid general performance overhead.

Additional context

[antfu]

Maybe we could refactor this out with

vueuse/packages/core/useActiveElement/index.ts

Lines 60 to 74 in 9399ba1

	if (triggerOnRemoval) {
	useMutationObserver(document as any, (mutations) => {
	mutations.filter(m => m.removedNodes.length)
	.map(n => Array.from(n.removedNodes))
	.flat()
	.forEach((node) => {
	if (node === activeElement.value)
	trigger()
	})
	}, {
	childList: true,
	subtree: true,
	})
	}

to have onElementRemoval composable to be reused for these two composables

[ben-lau]

Maybe we could refactor this out with

vueuse/packages/core/useActiveElement/index.ts

Lines 60 to 74 in 9399ba1

	if (triggerOnRemoval) {
	useMutationObserver(document as any, (mutations) => {
	mutations.filter(m => m.removedNodes.length)
	.map(n => Array.from(n.removedNodes))
	.flat()
	.forEach((node) => {
	if (node === activeElement.value)
	trigger()
	})
	}, {
	childList: true,
	subtree: true,
	})
	}

to have onElementRemoval composable to be reused for these two composables

Sure, do you mean make a new composition function first? I thought we were not accepting new features at the moment.

[antfu]

Yeah. This is fine as it doesn't increase the maintenance surface

[ben-lau]

Yeah. This is fine as it doesn't increase the maintenance surface

I've done add a new composition function onElementRemoval, and used it inside useActiveElement, useElementHover. You may review the code, I see there is something wrong in lint ci process.