RFR: 8345063: Centralize version number of the Gradle build file

[Kevin Rushforth]

On Tue, 26 Nov 2024 16:03:38 GMT, Nir Lisker <nlisker at openjdk.org> wrote:

> Centralizes version numbers in a single place. This is not the best way of doing it in Gradle, but it's an improvement that will simplify other changes. I used the `build.properties` file because other versions are already written there.
> 
> There are other version numbers in the build file, but they are not attached directly to a dependency. Mostly libav ones. I decided not to touch them.

Looks good.

-------------

Marked as reviewed by kcr (Lead).

PR Review: https://git.openjdk.org/jfx/pull/1649#pullrequestreview-2462371868