RFR: Merge jdk17

[Jesper Wilhelmsson]

Forwardport JDK 17 -> JDK 18

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Commit messages:
 - Merge
 - 8269150: UnicodeReader not translating \u005c\\u005d to \\]
 - 8271175: runtime/jni/FindClassUtf8/FindClassUtf8.java doesn't have to be run in othervm
 - 8271222: two runtime/Monitor tests don't check exit code
 - 8015886: java/awt/Focus/DeiconifiedFrameLoosesFocus/DeiconifiedFrameLoosesFocus.java sometimes failed on ubuntu

The webrevs contain the adjustments done while merging with regards to each parent branch:
 - master: https://webrevs.openjdk.java.net/?repo=jdk&pr=4907&range=00.0
 - jdk17: https://webrevs.openjdk.java.net/?repo=jdk&pr=4907&range=00.1

Changes: https://git.openjdk.java.net/jdk/pull/4907/files
  Stats: 118 lines in 6 files changed: 103 ins; 4 del; 11 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4907.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4907/head:pull/4907

PR: https://git.openjdk.java.net/jdk/pull/4907