RFR: 8231692: Test Infrastructure: enhance KeyEventFirer to inject keyEvents into scene

[Jeanette Winzenburg]

The issue is that firing keyEvents on a node that is not focusOwner might produce false green tests, please see the issue for details.

fix for https://bugs.openjdk.java.net/browse/JDK-8231692
- added contructor taking the scene
- changed event firing to use either the target directly or inject into
scene

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Commits:
 - aabea139: Test Infrastructure: enhance KeyEventFirer to inject keyEvents into

Changes: https://git.openjdk.java.net/jfx/pull/20/files
 Webrev: https://webrevs.openjdk.java.net/jfx/20/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8231692
  Stats: 263 lines in 2 files changed: 260 ins; 2 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx/pull/20.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/20/head:pull/20

PR: https://git.openjdk.java.net/jfx/pull/20