RFR: 8211234: Open-source simple test programs for FX / Swing interop

[Jayathirth D V]

This PR is for open-sourcing 2 closed toys EmbeddedSwing and HelloWorld.
JBS : https://bugs.openjdk.org/browse/JDK-8211234

1)EmbeddedSwing - a simple FX test app with a SwingNode containing a Swing application

2)HelloWorld contains 2 test apps :

- HelloJFXPanel - a simple Swing test app with a JButton and a JFXPanel containing an animated rectangle

- HelloJFXPanel2 - a simple Swing test app with a JButton and a JFXPanel containing a JavaFX Button and ComboBox (with Tooltips) 

These new test apps are added under apps/toys/ directory.

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Commit messages:
 - 8211234: Open-source simple test programs for FX / Swing interop

Changes: https://git.openjdk.org/jfx/pull/1572/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1572&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8211234
  Stats: 3379 lines in 18 files changed: 3373 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jfx/pull/1572.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1572/head:pull/1572

PR: https://git.openjdk.org/jfx/pull/1572