RFR: 8304911: Use OperatingSystem enum in some modules

[Roger Riggs]

With the addition of `jdk.internal.util.OperatingSystem` references to the system property `os.name` can be replaced.
This PR exports jdk.internal.util to:
 - java.prefs,
 - java.security.jgss,
 - java.smartcardio,
 - jdk.charsets,
 - jdk.net,
 - jdk.zipfs

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Commit messages:
 - In jdk.prefs module, Replace os.name with OperatingSystem enum
 - Use OperatingSystem methods instead of system property os.name

Changes: https://git.openjdk.org/jdk/pull/13335/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13335&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8304911
  Stats: 131 lines in 13 files changed: 24 ins; 54 del; 53 mod
  Patch: https://git.openjdk.org/jdk/pull/13335.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13335/head:pull/13335

PR: https://git.openjdk.org/jdk/pull/13335