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

[Andy Goryachev]

## ManualTestWindow

This facility provides a framework for manual tests to display test 
instructions, test pane, and Pass/Fail buttons.

A simple test would look like this:


public class SampleManualTest {
     public static void main(String[] args) throws Exception {
         ManualTestWindow.builder().
             title("Sample Manual Test").
             instructions(
                 """
                 Provide
                 multi-line instructions here.
                 """
             ).
             ui(() -> createTestUI()).
             buildAndRun();
     }

     private static Node createTestUI() {
         return new Label("Test UI");
     }
}


Resulting application window:

![ManualTestWindow](https://github.com/openjdk/jfx/assets/107069028/15b34a8f-cb0d-4469-85bc-ec5962e448c7)

Readme:

https://github.com/openjdk/jfx/blob/1cc095049be3773e1211ad570eb2285f08f25cec/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 and moved sources to src/, still 
using the default package).

Q: Do we want to avoid using the default package?

Q: What other features can be added to the test window?

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

Commit messages:
 - whitespace
 - Merge branch 'master' into 8319555.manual
 - manual test window
 - fixed text manual test setup

Changes: https://git.openjdk.org/jfx/pull/1413/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1413&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8319555
  Stats: 535 lines in 15 files changed: 426 ins; 107 del; 2 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