RFR: 8321434: Update Gradle to 8.5

Fri Dec 8 00:59:40 UTC 2023

Gradle 8.5.0 released on Nov 29, 2023, supports JDK 21.
We need to update Gradle to 8.5 in order to update the boot JDK.
There are not API level changes in Gradle that we need to work on, hence the change is only Gradle version update.

Also, merging the PR with boot jdk update to 21.0.1 b12

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Commit messages:
 - gradle update 8.5, boot jdk 19.0.1 b12

Changes: https://git.openjdk.org/jfx/pull/1300/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1300&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8321434
  Stats: 14 lines in 4 files changed: 0 ins; 0 del; 14 mod
  Patch: https://git.openjdk.org/jfx/pull/1300.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1300/head:pull/1300

PR: https://git.openjdk.org/jfx/pull/1300