<Swing Dev> RFR: Merge jdk16

[Jesper Wilhelmsson]

Forwardport JDK 16 -> JDK 17

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Commit messages:
 - Merge
 - 8259757: add a regression test for 8259353 and 8259601
 - 8259732: JDK 16 L10n resource file update - msg drop 10

The webrevs contain the adjustments done while merging with regards to each parent branch:
 - master: https://webrevs.openjdk.java.net/?repo=jdk&pr=2176&range=00.0
 - jdk16: https://webrevs.openjdk.java.net/?repo=jdk&pr=2176&range=00.1

Changes: https://git.openjdk.java.net/jdk/pull/2176/files
  Stats: 296 lines in 31 files changed: 200 ins; 16 del; 80 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2176.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2176/head:pull/2176

PR: https://git.openjdk.java.net/jdk/pull/2176