[jdk17u] RFR: 8267666: Add option to jcmd GC.heap_dump to use existing file

[Christoph Langer]

Clean backport of this enhancement. CSR includes update releases.

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Commit messages:
 - Backport 7cbb67a3f8adc83a5b51c092a66480d7b22a6bea

Changes: https://git.openjdk.java.net/jdk17u/pull/2/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17u&pr=2&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8267666
  Stats: 35 lines in 11 files changed: 12 ins; 8 del; 15 mod
  Patch: https://git.openjdk.java.net/jdk17u/pull/2.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17u pull/2/head:pull/2

PR: https://git.openjdk.java.net/jdk17u/pull/2