RFR: 7903928: update build.gradle to use JDK 23 [v2]

[Nizar Benalla]

> We've updated native makefile to use JDK 23 (https://github.com/openjdk/jextract/commit/0b89a462146940a2ec90e34eeb5df3d46d8980d2), 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".
> 
> The mismatch has caused [some confusion](https://mail.openjdk.org/pipermail/panama-dev/2025-January/020915.html).
> 
> This patch to rename references to `jdk22_home` to `jdk_home`, the jextract version has now been bumped to `23`.
> 
> This PR has been obtained through a `git merge --squash` of #271.
> 
> TIA

Nizar Benalla has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:

 - refer to JDK 23
 - Merge remote-tracking branch 'upstream/master' into pull/271
 - Updates based on review comment in pr/271
 - jextract PR #271

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

Changes:
  - all: https://git.openjdk.org/jextract/pull/275/files
  - new: https://git.openjdk.org/jextract/pull/275/files/f0e4b1ab..703b3d8a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jextract&pr=275&range=01
 - incr: https://webrevs.openjdk.org/?repo=jextract&pr=275&range=00-01

  Stats: 103 lines in 70 files changed: 8 ins; 1 del; 94 mod
  Patch: https://git.openjdk.org/jextract/pull/275.diff
  Fetch: git fetch https://git.openjdk.org/jextract.git pull/275/head:pull/275

PR: https://git.openjdk.org/jextract/pull/275