RFR: 8364764: java/nio/channels/vthread/BlockingChannelOps.java subtests timed out

[Alan Bateman]

4 tests (testSocketChannelWriteAsyncClose, testSocketChannelWriteInterrupt, testPipeWriteAsyncClose testPipeWriteInterrupt) test async close/interrupt when a virtual thread is blocked in write. This is difficult to test as the target thread may wakeup with bytes written (so it returns the number of bytes written rather than throw).  The test is changed to "nudge" the writer a few times so that the writer eventually wakes up with no bytes written.

Additionally, two tests are added to test async shutdownInput and shutdownOutput.

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Commit messages:
 - More robustness
 - Merge branch 'master' into JDK-8364764
 - Initial commit

Changes: https://git.openjdk.org/jdk/pull/26847/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26847&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8364764
  Stats: 111 lines in 1 file changed: 80 ins; 2 del; 29 mod
  Patch: https://git.openjdk.org/jdk/pull/26847.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26847/head:pull/26847

PR: https://git.openjdk.org/jdk/pull/26847