RFR: 8274274: Update JUnit to version 5.8.1 [v6]

[Kevin Rushforth]

On Mon, 15 Nov 2021 22:37:09 GMT, John Hendrikx <jhendrikx at openjdk.org> wrote:

>> I've added JUnit 5 as a test dependency and made sure that the JUnit 4 tests still work.  Also added a single JUnit 5 tests, and confirmed it works.
>> 
>> I've updated the Eclipse project file for the base module only.
>
> John Hendrikx has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Fix white space error
>  - Allow apiguardian as dependency

I also was able to make the (minor) changes needed to our closed build to use the `4.13.2` jar files.

As a note to other committers: Given that this is a third-party update, and that I need to integrate a coordinated closed change, I will sponsor this once it is ready. Please don't sponsor it even if it appears to be waiting for a while.

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PR: https://git.openjdk.java.net/jfx/pull/633