RFR: 7903928: update build.gradle to use JDK 23

[Athijegannathan Sundararajan]

We've updated native makefile to use JDK 23 (
https://github.com/openjdk/jextract/commit/0b89a462146940a2ec90e34eeb5df3d46d8980d2 )

While build.gradle works & expects jdk 23, it still refers to JDK var as "jdk22_home" and passes --release to be 22. Also jextract version is "22".

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

Commit messages:
 - 7903928: update build.gradle to use JDK 23

Changes: https://git.openjdk.org/jextract/pull/271/files
  Webrev: https://webrevs.openjdk.org/?repo=jextract&pr=271&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903928
  Stats: 8 lines in 1 file changed: 1 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jextract/pull/271.diff
  Fetch: git fetch https://git.openjdk.org/jextract.git pull/271/head:pull/271

PR: https://git.openjdk.org/jextract/pull/271