Update Gradle (Wrapper) to 8.14

[ebbez]

Updates Gradle to 8.14 (and removes the wrapper { block from build.gradle since it went un-updated).

(The Gradle setup action should verify the integrity of the Gradle Wrapper jar file, but if you want to verify manually you can find the checksums on https://gradle.org/release-checksums/ )

[berry120]

I have a vague feeling the reason we didn't upgrade before was because the snapcraft image failed with a newer gradle version for some reason (seems like it blocked head requests that seemed to be used on newer versions) - but this was a while back, so I might merge in a bit just to see if it functions, but if not would have to back it out.

[ebbez]

Gradle 8.14 was released 2 days ago so I bumped the version to 8.14.

If it breaks Snaps then it's no good so definitely feel free to revert it then! I am trying to get for some needed dependencies/build tools up to date, mainly because DK/JFX 24 are probably needed for Linux due to the shrinking maximized window issue, and Gradle 8.14 supports JDK 24 officially, but of course the pre-existing installers take priority.

[berry120]

Let's merge and see what happens to the snaps!