RFR: 8332124: Jcmd should recognise options that look like requests for help [v6]

[Sonia Zaldana Calles]

> Hi all, 
> 
> This PR addresses [8332124](https://bugs.openjdk.org/browse/JDK-8332124) enabling jcmd to accept "help" as an argument to subcommands. 
> 
> Testing: 
> - [x] Verified running `jcmd 4711 VM.metaspace help` works along with other subcommands. 
> - [x] Added test case passes. 
> 
> Thanks, 
> Sonia

Sonia Zaldana Calles has updated the pull request incrementally with two additional commits since the last revision:

 - Updating comments
 - Enabling -help to work as well. Updating test cases

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/19776/files
  - new: https://git.openjdk.org/jdk/pull/19776/files/4e2a4493..56203e57

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19776&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19776&range=04-05

  Stats: 41 lines in 3 files changed: 32 ins; 3 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/19776.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19776/head:pull/19776

PR: https://git.openjdk.org/jdk/pull/19776