RFR: 8296246: Update Unicode Data Files to Version 15.1.0 [v3]

[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 Conjunct Break specified in the latest [Unicode Annex #29 ("Unicode Text Segmentation")](https://unicode.org/reports/tr29/) is included. A corresponding CSR has also been drafted.

Naoto Sato 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 10 additional commits since the last revision:

 - Fix GensrcRegex.gmk
 - Merge branch 'master' into JDK-8296246-Unicode15.1
 - Update make/jdk/src/classes/build/tools/generateextraproperties/GenerateExtraProperties.java
   
   Co-authored-by: Andrey Turbanov <turbanoff at gmail.com>
 - Update make/jdk/src/classes/build/tools/generateextraproperties/GenerateExtraProperties.java
   
   Co-authored-by: Andrey Turbanov <turbanoff at gmail.com>
 - TR29 final version
 - .md file update
 - Final 8/28
 - Draft 8/11
 - GenerateExtraProperties tool
 - initial commit

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/15728/files
  - new: https://git.openjdk.org/jdk/pull/15728/files/10527c07..31e397ce

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15728&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15728&range=01-02

  Stats: 41849 lines in 830 files changed: 7552 ins; 3478 del; 30819 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