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

[John Hendrikx]

> 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

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Changes:
  - all: https://git.openjdk.java.net/jfx/pull/633/files
  - new: https://git.openjdk.java.net/jfx/pull/633/files/7d56bcd0..c5b76ee8

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=633&range=05
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=633&range=04-05

  Stats: 15 lines in 2 files changed: 8 ins; 3 del; 4 mod
  Patch: https://git.openjdk.java.net/jfx/pull/633.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/633/head:pull/633

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