Target macos 12 and use macos 13 in CI

[smola]

Release changes:

• As of this PR, our release binaries target macos 12.7. We used to target macos 11.6 for the JNI bindings, but that was pointless since libddwaf 1.21.0, which targeted macos 12.7. So now both minimum targets are in sync.

CI changes:

• Move all macos-12 jobs to macos-13. macos 12 was deprecated by GitHub Actions. We use Xcode 14 here, see Fix build on macos-14 libddwaf#349.
• Enable test jobs on recent macos versions, which were previously disabled because of a JDK bug (JDK-8205076, now fixed).

Development changes:

• Local builds (as documented in the readme) now target macos 14. This is to allow building on macos 15, which does not provide an old enough Xcode. This change is tested in CI with macos 15. Note these builds should never be used in releases.

APPSEC-56754