RFR: 8272118: ListViewSkin et al: must not cancel edit on scrolling

[Jeanette Winzenburg]

Issue was that mouse pressed on the scrollbars of all virtualized controls cancelled the edit. That's inconsistent with other scroll triggers (mouseWheel, programmatic). Fixed by removing the cancel.

Added tests that failed/passed before/after the fix. Also added tests that passed both before/after to guarantee that required functionality of the mouse pressed (= requesting focus on the control if needed) is still working.

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Commit messages:
 - 8272118: ListViewSkin et al: must not cancel edit on scrolling

Changes: https://git.openjdk.java.net/jfx/pull/682/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=682&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8272118
  Stats: 594 lines in 6 files changed: 566 ins; 28 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx/pull/682.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/682/head:pull/682

PR: https://git.openjdk.java.net/jfx/pull/682