RFR: 8290844: Add Skin.install() method [v15]

[Andy Goryachev]

On Thu, 27 Oct 2022 23:36:21 GMT, Andy Goryachev <angorya at openjdk.org> wrote:

>> We don't want to mix JUnit 4 and JUnit 5 in the same file, and it seems out of scope to change this existing test class to use Junit5.
>
> Are we mixing?  I believe the tests have been converted to JUnit5 some time ago, [JDK-8292678](https://bugs.openjdk.org/browse/JDK-8292678) at least in Eclipse.
> I think this is a valid change.

(and it was me who added @Test(expected=IllegalArgumentException.class) test)

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PR: https://git.openjdk.org/jfx/pull/845