RFR: 8211247: Open-source simple test programs for FX / SWT interop

[Jayathirth D V]

This PR is for open-sourcing HelloFXCanvas test app.
JBS : https://bugs.openjdk.org/browse/JDK-8211247 
It is an SWT app with SWT button and an FXCanvas with animated rectangle.
This is used on our integration testing.

This test is now moved to apps/toys, please refer to apps/toys/HelloFXCanvas/README.txt on how to run this toy.

Also this toy hangs on exit in macOS and it crashes on Wayland in Ubuntu 24.04, for which separate bugs will be raised.

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Commit messages:
 - 8211247: Open-source simple test programs for FX / SWT interop

Changes: https://git.openjdk.org/jfx/pull/1571/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1571&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8211247
  Stats: 1266 lines in 9 files changed: 1263 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jfx/pull/1571.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1571/head:pull/1571

PR: https://git.openjdk.org/jfx/pull/1571