<i18n dev> RFR: 8296246: Update Unicode Data Files to Version 15.1.0

[Naoto Sato]

This PR is to incorporate the latest Unicode 15.1, which was released yesterday. Besides the usual character data update, an upgraded implementation of RegEx which reflects the Indic Consonant Break specified in the latest Unicode Annex #29 ("Unicode Text Segmentation") is included. A corresponding CSR has also been drafted.

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Commit messages:
 - TR29 final version
 - .md file update
 - Final 8/28
 - Draft 8/11
 - GenerateExtraProperties tool
 - initial commit

Changes: https://git.openjdk.org/jdk/pull/15728/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15728&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8296246
  Stats: 1529 lines in 22 files changed: 1298 ins; 15 del; 216 mod
  Patch: https://git.openjdk.org/jdk/pull/15728.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15728/head:pull/15728

PR: https://git.openjdk.org/jdk/pull/15728