RFR: 8345136: Update JDK_DOCS property to point to JDK 23 docs

[Ambarish Rapte]

On Fri, 13 Dec 2024 00:52:00 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

> Update the docs bundle to point to the JDK 23 docs (we're currently pointing to JDK 21).
> 
> I will need to also download and host a zip bundle and add its checksum to gradle/verification-metadata.xml to avoid breaking our internal CI build.
> 
> As mentioned in [JDK-8325873](https://bugs.openjdk.org/browse/JDK-8325873) when we updated the docs to use JDK 21, we should do this as a part of updating the boot JDK. To facilitate this, and to move more version number properties to a common place, I will create a new `jdk.docs.version` property in `build.properties` and put it near the `jfx.build.jdk.version` property.
> 
> Both the GHA build and our  CI build are successful.

LGTM, tested with a local build.
Having a separate property offers flexibility if ever we require it to be different than `jfx-build.jdk.version`, otherwise we could reuse property `jfx-build.jdk.version`.

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Marked as reviewed by arapte (Reviewer).

PR Review: https://git.openjdk.org/jfx/pull/1663#pullrequestreview-2505226654