RFR: 8310923: Refactor Currency tests to use JUnit [v3]

[Justin Lu]

> Please review this PR which refactors Currency tests to use JUnit.
> 
> The most significant change occurs in `ValidateISO4217.java`. Other changes to this file excluding the JUnit refactoring include
> 
> - Tests are no longer dependent on each other (order of execution does not matter)
> - Testing does not occur at the same time as data generation (The data is fully generated before any tests are executed)
> - Various cleanup (dead-code, clarifying comments, more descriptive method and var names)
> 
> `Bug4512215.java` now renamed to `MinorUndefinedCodes` was updated to remove redundant testing, and the file changed to focus on testing minor undefined currency codes instead.

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

 - Rename Bug8154295.java as NumCodeAsStringTest.java
 - Re-include the data version check

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/14682/files
  - new: https://git.openjdk.org/jdk/pull/14682/files/bff5cc6c..3975c57f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=14682&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=14682&range=01-02

  Stats: 8 lines in 2 files changed: 6 ins; 0 del; 2 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