RFR: 8319555: [TestBug] Utility for creating instruction window for manual tests [v8]

[Andy Goryachev]

> ## ManualTestWindow
> 
> This facility provides the base class for manual tests which displays the test instructions,
> the UI under test, and the Pass/Fail buttons.
> 
> Example:
> 
> 
> public class ManualTestExample extends ManualTestWindow {
>     public ManualTestExample() {
>         super(
>             "Manual Test Example",
>             """
>             Instructions:
>             1. you will see a button named "Test"
>             2. press the button
>             3. verify that the button can be pressed""",
>             400, 250
>         );
>     }
> 
>     public static void main(String[] args) throws Exception {
>         launch(args);
>     }
> 
>     @Override
>     protected Node createContent() {
>         return new Button("Test");
>     }
> }
> 
> 
> Resulting application window:
> 
> ![ManualTestWindow](https://github.com/openjdk/jfx/assets/107069028/fa29ce47-1ca3-458e-91e9-472da43cd724)
> 
> Readme:
> 
> https://github.com/andy-goryachev-oracle/jfx/blob/8319555.manual/tests/manual/util/README.md
> 
> @prrace 's test EmojiTest has been converted to use the new test window as a demonstration (also fixed the Eclipse project so it works now).
> 
> Q: What other features can be added to the test window?
> 
> Edit: the sources are left in their original place at the root of the project.

Andy Goryachev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 14 additional commits since the last revision:

 - Merge remote-tracking branch 'origin/master' into 8319555.manual
 - Merge remote-tracking branch 'origin/8319555.manual' into 8319555.manual
 - removed example
 - cleanup
 - whitespace
 - extends application
 - works
 - .
 - sources moved back
 - Merge branch 'master' into 8319555.manual
 - ... and 4 more: https://git.openjdk.org/jfx/compare/d9b9a20e...45e53102

-------------

Changes:
  - all: https://git.openjdk.org/jfx/pull/1413/files
  - new: https://git.openjdk.org/jfx/pull/1413/files/a8fc661b..45e53102

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1413&range=07
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1413&range=06-07

  Stats: 1325 lines in 28 files changed: 1113 ins; 64 del; 148 mod
  Patch: https://git.openjdk.org/jfx/pull/1413.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1413/head:pull/1413

PR: https://git.openjdk.org/jfx/pull/1413