[jdk11u-dev] RFR: 8233790: Forward output from heap dumper to jcmd/jmap

[BuddyLiao]

Backport of the heap dump enhancement: Forward output from heap dumper to jcmd/jmap

Patch did not apply cleanly, I had to resolve/modify
src/hotspot/share/services/diagnosticCommand.cpp
src/hotspot/share/services/heapDumper.cpp
src/hotspot/share/services/heapDumper.hpp

since patch 7cbb67a3f8adc83a5b51c092a66480d7b22a6bea is backport before this one, so this patch can't backport cleanly

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Commit messages:
 - Backport b2a967382980bbaca2c2f7d08eab565024ede40e

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/256/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=256&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8233790
  Stats: 47 lines in 4 files changed: 3 ins; 29 del; 15 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/256.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/256/head:pull/256

PR: https://git.openjdk.java.net/jdk11u-dev/pull/256