RFR: 8318613: ChoiceFormat patterns are not well tested [v2]

[Justin Lu]

> Please review this PR which adds a test for ChoiceFormat intended to test a wide range of ChoiceFormat patterns.
> 
> The existing test _Bug4387255_ only tests a singular basic pattern and does not test for incorrect patterns either.
> 
> The new test checks 
> 
> - both correct and incorrect patterns
> - the behavior of incorrect patterns that either throw an IllegalArgumentException or discard the incorrect portion
> - the case of formatting with an empty pattern (that leads to empty limits and formats)

Justin Lu has updated the pull request incrementally with one additional commit since the last revision:

  implement feedback

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Changes:
  - all: https://git.openjdk.org/jdk/pull/16324/files
  - new: https://git.openjdk.org/jdk/pull/16324/files/036cbfa1..2fb5a1a6

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16324&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16324&range=00-01

  Stats: 34 lines in 1 file changed: 11 ins; 0 del; 23 mod
  Patch: https://git.openjdk.org/jdk/pull/16324.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16324/head:pull/16324

PR: https://git.openjdk.org/jdk/pull/16324