RFR: 8349373: Support JavaFX preview features [v3]

[Andy Goryachev]

On Fri, 7 Feb 2025 09:16:54 GMT, Michael Strauß <mstrauss at openjdk.org> wrote:

>> This PR contains a definition of preview features for JavaFX, as well as a helper class to verify that an application has opted into preview features.
>
> Michael Strauß has updated the pull request incrementally with four additional commits since the last revision:
> 
>  - javadoc
>  - remove supporting documentation
>  - warning can't be suppressed
>  - initialize PreviewFeature early

> That method would unlock preview features only if the version passed in matches the runtime feature version.

what would happen if we don't add this logic?  the app will exit with `ClassNotFoundException` or some runtime error?

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PR Comment: https://git.openjdk.org/jfx/pull/1359#issuecomment-2659938528