RFR: 8286261: Selection of non-expanded non-leaf treeItem grows unexpectedly when adding two-level descendants

[Jose Pereda]

This PR extends the check if a treeItem is expanded to all its ancestors, as in case one ancestor is collapsed, all its children will be hidden.

4 tests are included, two for TreeView and two for TreeTableView.

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Commit messages:
 - Check if treeItem and all its ancestors are expanded, including tests

Changes: https://git.openjdk.java.net/jfx/pull/791/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx&pr=791&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8286261
  Stats: 179 lines in 5 files changed: 171 ins; 0 del; 8 mod
  Patch: https://git.openjdk.java.net/jfx/pull/791.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/791/head:pull/791

PR: https://git.openjdk.java.net/jfx/pull/791