<i18n dev> RFR: 8300794: Use @snippet in java.util:i18n

[Justin Lu]

Please review this javadoc only change which uses `@snippet` and `@linkplain` in i18n related util packages.

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Commit messages:
 - copyright years
 - property resource bundle changes
 - list resource bundle changes
 - resource bundle changes
 - currency changes
 - locale changes

Changes: https://git.openjdk.org/jdk/pull/13920/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13920&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8300794
  Stats: 127 lines in 5 files changed: 7 ins; 24 del; 96 mod
  Patch: https://git.openjdk.org/jdk/pull/13920.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13920/head:pull/13920

PR: https://git.openjdk.org/jdk/pull/13920