Proposing accessor methods to Emoji properties defined in [Unicode Technical Standard #51](https://unicode.org/reports/tr51/) in `java.lang.Character` class. This is per a request from the client group, as well as refining the currently existing ad-hoc emoji implementation in regex. A CSR has also been drafted, and I would appreciate reviews for it too.
------------- Commit messages: - Clean-up - UTR -> UTS - prepared javadoc - added a test case - 8303018: Unicode Emoji Properties Changes: https://git.openjdk.org/jdk/pull/13006/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13006&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8303018 Stats: 869 lines in 19 files changed: 592 ins; 254 del; 23 mod Patch: https://git.openjdk.org/jdk/pull/13006.diff Fetch: git fetch https://git.openjdk.org/jdk pull/13006/head:pull/13006 PR: https://git.openjdk.org/jdk/pull/13006
