RFR: 8274274: Update JavaFX test framework to JUnit 5 [v2]

[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 refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:

  Add JUnit 5

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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/072494e6..233fdb80

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=633&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=633&range=00-01

  Stats: 20 lines in 1 file changed: 0 ins; 20 del; 0 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