RFR: 8311653: Modify -XshowSettings launcher behavior [v2]

[Sean Coffey]

> Modify the -XshowSettings launcher option to print non-verbose settings details of all components by default. Verbose settings details will be printed via the -XshowSettings:all option. Modify the -XshowSettings option to reject bad values passed to it. Print an error message in such scenarios and abort the VM launch.

Sean Coffey has updated the pull request incrementally with two additional commits since the last revision:

 - Incorporate review feedback
 - modify -X output for :all

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Changes:
  - all: https://git.openjdk.org/jdk/pull/15001/files
  - new: https://git.openjdk.org/jdk/pull/15001/files/6994dd04..688b856d

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15001&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15001&range=00-01

  Stats: 125 lines in 4 files changed: 78 ins; 13 del; 34 mod
  Patch: https://git.openjdk.org/jdk/pull/15001.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15001/head:pull/15001

PR: https://git.openjdk.org/jdk/pull/15001