fix(useMagicKeys): also clear 'current' on @focus|@blur

[hartmut-co-uk]

Description

On macos when some keys are pressed in combo(cmd+p) open a dialog and the keyup is not triggered and the current keep a wrong state.
This fix now also clears the current: Set<string> with the existing reset() function (added in prior #1755).

fixes #1350

Additional context

ref: #1755

Testing / Reproduction, see description of #1350...

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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• Read the Contributing Guidelines.
• Read the Pull Request Guidelines.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
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• Ideally, include relevant tests that fail without this PR but pass with it.

[hartmut-co-uk]

Here's a demo of the current bug, recorded on https://vueuse.org/core/usemagickeys/#demo

If you leave the window though e.g.

• meta+shift+c
• meta+f (find on page)
• meta+tab (switch OS windows)

And then come back to the page/tab (focus). The previous keys are still in place and stay there until the same keys are pressed again...

[Thinkro]

Does this fix these issues?
#2298
#1312
#946
#915
#491

This has been referenced so many times now, and i see 2 pull requests trying to fix it, addition to this one.

[hartmut-co-uk]

Hi, I've tested locally one of the issues mentioned with Meta key. This PR does not fix issues related to MacOS / Meta key as far as I can tell, e.g. I can still reproduce the issue mentioned here:

But it still fixes issues as described (#1350) regarding to window @focus/@blur.