RFR: 8370203 - Add jcmd AOT.end_recording diagnostic command [v3]

[Mat Carter]

> Add jcmd AOT.end_recording diagnostic command.  When this command is issued, a targeted JVM that is currently recording AOT information will stop recording.  Existing functionality is preserved: when stopped the JVM will create the required artifacts based on the execution mode.  Conveniently as the application running on the JVM has not stopped (as was previously the only way to stop recording), the application will resume execution after the artifacts have been generated.
> 
> The command will report back to the user one of the following messages depending on the state of the JVM:
> 
> - Error! Not a recording run
> - Error! Not recording
> - Recording ended successfully
> - Error! Failed to end recording
> 
> It follows that issues the command to a JVM that is recording, twice in succession, should (baring internal errors) would produce the following two responses:
> 
> - Recording ended successfully
> - Error! Not recording
> 
> Passes tier1 on linux (x64) and windows (x64)

Mat Carter has updated the pull request incrementally with one additional commit since the last revision:

  Document use of DiagnosticCommand

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Changes:
  - all: https://git.openjdk.org/jdk/pull/27965/files
  - new: https://git.openjdk.org/jdk/pull/27965/files/7b7e2f7e..cdd1f1d4

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27965&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27965&range=01-02

  Stats: 32 lines in 1 file changed: 32 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/27965.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27965/head:pull/27965

PR: https://git.openjdk.org/jdk/pull/27965