RFR: 8357847: WindowsAsynchronousFileChannelImpl should support FFM Buffers

[Brian Burkhalter]

Acquire the scope of a direct buffer before it is used and release it after the task has finished with it, whether the task execution is immediate or pended.

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Commit messages:
 - 8357847: WindowsAsynchronousFileChannelImpl should support FFM Buffers

Changes: https://git.openjdk.org/jdk/pull/25531/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25531&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8357847
  Stats: 23 lines in 1 file changed: 6 ins; 0 del; 17 mod
  Patch: https://git.openjdk.org/jdk/pull/25531.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25531/head:pull/25531

PR: https://git.openjdk.org/jdk/pull/25531