RFR: 8327246: Add a jcmd diagnostic command to list the jar files loaded by a process

[Larry Cable]

modified the pre-existing VM.classes jcmd to add a 'location' option, that when specified, will (natively) attempt to obtain the value (if non-null) of the location URL of the CodeSource of each classes ProtectionDomain.

effectively:

someObject.getClass().getProtectionDomain().getCodeSource().getLocation().toExternalForm()

(where interim oops are null-checked)

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Commit messages:
 - JDK-8327246: Add a jcmd diagnostic command to list the jar files loaded by a process

Changes: https://git.openjdk.org/jdk/pull/29048/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29048&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8327246
  Stats: 49 lines in 4 files changed: 41 ins; 0 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/29048.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29048/head:pull/29048

PR: https://git.openjdk.org/jdk/pull/29048