RFR: 8304912: Use OperatingSystem enum in java.desktop module [v4]

[Roger Riggs]

> Update classes in the java.desktop module to use the jdk.internal.util.OperatingSystem enum instead of the `os.name` system property to select OS specific behaviors.

Roger Riggs has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains seven additional commits since the last revision:

 - Refactor to use sun.awt.OSInfo instead of system property os.name.
   Modify OSInfo to use jdk.internal.util.OperatingSystem.
   Modify OSInfo.getOSType() to use a cached value and not require doPriv
   or throw SecurityException
 - Merge branch 'master' into 8304912-use-os-desktop
 - Update copyright
   Replaced a few more uses of os.name.
 - Merge branch 'master' into 8304912-use-os-desktop
 - Use OperatingSystem.isAix
 - Remove unused os.arch system property
 - Apply OperatingSystem enum instead of os.name to java.desktop module

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13213/files
  - new: https://git.openjdk.org/jdk/pull/13213/files/8f0b918e..a81dd830

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13213&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13213&range=02-03

  Stats: 5111 lines in 137 files changed: 3978 ins; 559 del; 574 mod
  Patch: https://git.openjdk.org/jdk/pull/13213.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13213/head:pull/13213

PR: https://git.openjdk.org/jdk/pull/13213