RFR: 8268081: Support for Unicode 14

[Naoto Sato]

Please review the changes for upgrading the Unicode support in the JDK, from version 13 to version 14. Corresponding CSR has also been drafted.

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Commit messages:
 - Amend unicode.md and icu.md files
 - Minor fixup
 - Merge branch 'master' into unicode
 - Copyright year to 2022
 - ICU4J 70.1
 - 18 -> 19
 - Merge branch 'master' into unicode
 - Unicode 14.0.0 (final)
 - UCD ver. 14.0 (beta) / Unicode Text Segmentation rev. 38 (draft)
 - ICU4J 69.1

Changes: https://git.openjdk.java.net/jdk/pull/6974/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6974&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268081
  Stats: 3443 lines in 41 files changed: 2353 ins; 101 del; 989 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6974.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6974/head:pull/6974

PR: https://git.openjdk.java.net/jdk/pull/6974