RFR: 8319055: JCMD should not buffer the whole output of commands [v6]

[Alex Menkov]

> The fix implements streaming output support for attach protocol.
> See JBS issue for evaluation, summary of the changes in the 1st comment.
> Testing: tier1..4,hs-tier5-svc

Alex Menkov has updated the pull request incrementally with one additional commit since the last revision:

  restore ThreadBlockInVM in complete

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Changes:
  - all: https://git.openjdk.org/jdk/pull/23405/files
  - new: https://git.openjdk.org/jdk/pull/23405/files/2a3d4346..ed569cc7

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23405&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23405&range=04-05

  Stats: 2 lines in 1 file changed: 2 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/23405.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23405/head:pull/23405

PR: https://git.openjdk.org/jdk/pull/23405