RFR: Draft: 8274274: Update JavaFX test framework to JUnit 5 [v3]

[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:

 - Add copyright header
 - Remove apiguardian and hamcrest dependencies as not strictly required

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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/233fdb80..d0d7969e

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=633&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=633&range=01-02

  Stats: 53 lines in 3 files changed: 30 ins; 21 del; 2 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