RFR: 8218781 : Localized names for Japanese Era Reiwa in COMPAT provider

[li.jiang at oracle.com]

Hi all,

Please review the change to update the l10n names for Japanese era Reiwa 
in JDK COMPAT provider. The l10n names come from the CLDR 35.1, please 
refer this unicode chart[1] for l10n definitions.

Bug:
https://bugs.openjdk.java.net/browse/JDK-8218781
Webrev:
http://cr.openjdk.java.net/~ljiang/8218781/webrev.00/

In this change,
  - update the l10n names if they are defined in CLDR 35.1.
  - update the l10n names to Reiwa, Reiwa, R for FULL, SHORT, NARROW 
style respectively.
  - In FormatData_th.java, the localized single character was used for 
previous eras. But we don't find the corresponding name in CLDR 35.1. 
Update it to 'R' according to CLDR 35.1.

[1] 
https://www.unicode.org/cldr/charts/latest/by_type/date_&_time.japanese.html


Thanks,
Leo