RFR: 8304913: Use OperatingSystem, Architecture, and Version in jlink

[Roger Riggs]

Refactor the Platform class of jlink to use jdk.internal.util OperatingSystem and Architecture instead of os.name and os.arch. 
They are direct replacements for the Platform enums except for UNKNOWN; its use is refactored to report errors via exceptions.

Neither os.name nor os.arch should be assumed to be changeable; 
one test case is removed because it assumes os.name can be changed on the command line.

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Commit messages:
 - Merge branch 'master' into 8304913-os-arch-jlink
 - Minor cleanup
 - Merge branch 'master' into 8304913-os-arch-jlink
 - 8304913: Use OperatingSystem, Architecture, and Version in jlink
 - Simplify exception handling
 - Simplify version parsing
 - 8306678: Replace use of os.version with an internal Version record
 - Use and test of "s390" verified by reviewer.
 - Merge branch 'master' into 8304915-arch-enum
 - Merge branch 'master' into 8304915-arch-enum
 - ... and 16 more: https://git.openjdk.org/jdk/compare/fc76687c...8b14b48e

Changes: https://git.openjdk.org/jdk/pull/13585/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13585&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8304913
  Stats: 126 lines in 7 files changed: 16 ins; 79 del; 31 mod
  Patch: https://git.openjdk.org/jdk/pull/13585.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13585/head:pull/13585

PR: https://git.openjdk.org/jdk/pull/13585