<i18n dev> RFR: JDK-8322235: Split up and improve LocaleProvidersRun [v2]

[Justin Lu]

> Please review this PR which splits up the _LocaleProvidersRun_ test file for performance and maintenance reasons.
> 
> _LocaleProvidersRun_ which tests against the various Locale Providers (CLDR, HOST, SPI, etc.) was getting rather long, as all related bugs were added to the single test file. To improve maintainability, this change splits up the single test file into separate test files focused on specific areas (ex: _j.text.Format_).  The original _LocaleProvidersRun_ test file remains and is used for more general Locale Provider testing such as the adapter loading.
> 
> In addition, the previously single test file used to suffer from performance issues, as each test method had to launch a new JVM (since Locale Providers are set at Java startup time). With this change, these tests files can be ran with VM flags and not cause timeout, thus `@requires vm.flagless` is no longer needed (Tiers 6-8 tested).
> 
> Other updates
> - For OS/locale specific tests, the OS/locale is now checked before (not after) launching a JVM
> - For tests that are meant to be tested against specific locales, additional run invocations were added with the appropiate locale to guarantee a run (ex: `@run junit/othervm -Duser.language=en -Duser.country=GB`)
> - Added comments for each test method

Justin Lu has updated the pull request incrementally with two additional commits since the last revision:

 - cleanup comments
 - provide both SPI classes under build for relevant test files

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/17257/files
  - new: https://git.openjdk.org/jdk/pull/17257/files/b38b9909..a75237dc

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17257&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17257&range=00-01

  Stats: 23 lines in 5 files changed: 12 ins; 0 del; 11 mod
  Patch: https://git.openjdk.org/jdk/pull/17257.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17257/head:pull/17257

PR: https://git.openjdk.org/jdk/pull/17257