RFR: 7903202: enable macOS CI checks

[Denys Makogon]

This adjustment modifies the build config by introducing
strategy matrix in order to enable builds from both Ubuntu and macOS.

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Commit messages:
 - renaming a job based on the given feedback
 - 7903202: enable macOS CI checks

Changes: https://git.openjdk.java.net/jextract/pull/45/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jextract&pr=45&range=00
  Issue: https://bugs.openjdk.java.net/browse/CODETOOLS-7903202
  Stats: 34 lines in 1 file changed: 22 ins; 0 del; 12 mod
  Patch: https://git.openjdk.java.net/jextract/pull/45.diff
  Fetch: git fetch https://git.openjdk.java.net/jextract pull/45/head:pull/45

PR: https://git.openjdk.java.net/jextract/pull/45