RFR: 8310923: Refactor Currency tests to use JUnit

Tue Jun 27 23:04:17 UTC 2023

Please review this PR which refactors the majority of Currency tests to use JUnit. (The leftover will be done in a separate PR).

The largest change is in `CurrencyTest.java`. To maintain the grouping of similar tests, JUnit nested classes were used.

I also believe that `Bug4512215.java` should probably be merged into `CurrencyTest.java` (since they both test getCurrencyCode() and getDefaultFractionDigits().

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Commit messages:
 - Remove trailing WS in Bug4512215.java
 - Rename Bug6807534.java as CurrencyNameProviderTest.java
 - Refactor CurrencyTest.java
 - Clarify CheckDataVersion.java
 - Refactor Bug8154295.java
 - Refactor Bug6807534.java
 - Refactor Bug4512215.java

Changes: https://git.openjdk.org/jdk/pull/14682/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14682&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8310923
  Stats: 613 lines in 6 files changed: 261 ins; 184 del; 168 mod
  Patch: https://git.openjdk.org/jdk/pull/14682.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14682/head:pull/14682

PR: https://git.openjdk.org/jdk/pull/14682