RFR: 2321: Prefer pattern matching for instanceof

[Pavel Rappo]

Pattern matching for `instanceof` was introduced in JDK 16, by JEP 394. It's already been used by new code in Skara, but the older code can benefit from it too.

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Commit messages:
 - Initial commit

Changes: https://git.openjdk.org/skara/pull/1673/files
  Webrev: https://webrevs.openjdk.org/?repo=skara&pr=1673&range=00
  Issue: https://bugs.openjdk.org/browse/SKARA-2321
  Stats: 156 lines in 52 files changed: 0 ins; 50 del; 106 mod
  Patch: https://git.openjdk.org/skara/pull/1673.diff
  Fetch: git fetch https://git.openjdk.org/skara.git pull/1673/head:pull/1673

PR: https://git.openjdk.org/skara/pull/1673