RFR: Merge openjdk/jdk21u:master

[William Kemper]

Merges tag jdk-21.0.6+6

-------------

Commit messages:
 - 8335912: Add an operation mode to the jar command when extracting to not overwriting existing files
 - 8342905: Thread.setContextClassloader from thread in FJP commonPool task no longer works after JDK-8327501 redux
 - 8344993: [21u] [REDO] Backport JDK-8327501 and JDK-8328366 to JDK 21
 - 8322809: SystemModulesMap::classNames and moduleNames arrays do not match the order
 - 8344628: Test TestEnableJVMCIProduct.java run with virtual thread intermittent fails
 - 8343285: java.lang.Process is unresponsive and CPU usage spikes to 100%
 - 8334475: UnsafeIntrinsicsTest.java#ZGenerationalDebug assert(!assert_on_failure) failed: Has low-order bits set
 - 8342409: [s390x] C1 unwind_handler fails to unlock synchronized methods with LM_MONITOR
 - 8345055: [21u] ProblemList failing rtm tests on ppc platforms
 - 8325906: Problemlist vmTestbase/vm/mlvm/meth/stress/compiler/deoptimize/Test.java#id1 until JDK-8320865 is fixed
 - ... and 1 more: https://git.openjdk.org/shenandoah-jdk21u/compare/50aa07ef...e45287d1

The merge commit only contains trivial merges, so no merge-specific webrevs have been generated.

Changes: https://git.openjdk.org/shenandoah-jdk21u/pull/140/files
  Stats: 956 lines in 22 files changed: 874 ins; 41 del; 41 mod
  Patch: https://git.openjdk.org/shenandoah-jdk21u/pull/140.diff
  Fetch: git fetch https://git.openjdk.org/shenandoah-jdk21u.git pull/140/head:pull/140

PR: https://git.openjdk.org/shenandoah-jdk21u/pull/140