feat: remove state slice when set as undefined

[JBBianchi]

Handles setting a slice state to undefined as removing the said slice.

Related to #1790

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[sdirix]

Thanks for the contribution ❤️

Please add test cases for the new behavior and make sure that the builds are green.

[JBBianchi]

Sorry, I did hammer a bit the CI, I don't have the environment installed locally so I could test before committing.

I hope it's good enough.

[coveralls]

coverage: 84.254%. remained the same when pulling 041db92 on JBBianchi:delete-on-set-undefined into 9acbbab on eclipsesource:master.

[sdirix]

Thanks for the contribution :)

[sdirix]

We can do an alpha release soon, so you can consume the changes 👍

[JBBianchi]

We can do an alpha release soon, so you can consume the changes 👍

That'd be great :)

[sdirix]

@JBBianchi 3.1.1-alpha.0 is released

[JBBianchi]

This feature seems to work as expected but this alpha-0 ships the bug reported (and fixed) in #2166 so I'll wait next release to actually use it.