Release Note: Support for Unicode 12.1

This release upgrades Unicode support to 12.1 which includes the following:
- `java.lang.Character` supports Unicode Character Database of 12.1 level, in which 12.0 adds 554 characters since 11.0, for a total of 137,928 characters. These additions include 4 new scripts, for a total of 150 scripts, as well as 61 new emoji characters. 12.1 adds exactly one character, `U+32FF SQUARE ERA NAME REIWA`, since 12.0.
- `java.text.Bidi` and `java.text.Normalizer` classes support 12.0 level of Unicode Standard Annexes, #9 and #15, respectively.
- `java.util.regex` package supports Extended Grapheme Clusters based on 12.0 level of Unicode Standard Annex #29