RFR: 8258592: Control labels in Dialogs are truncated at certain DPI scaling levels [v2]

[Jose Pereda]

> This PR is a follow up of [JDK-8199592](https://bugs.openjdk.java.net/browse/JDK-8199592). 
> 
> When using DPI scaling levels > 1, labels of controls get truncated when they are added to Dialogs which have an owner Window. 
> 
> To fix the issue, this PR binds dialog and owner window renderScale X, Y properties.
> 
> It also provides a system test that can be tested on Linux and Windows. Before applying the fix, the `Check` text of the checkboxes is rendered as `Che...`. With the fix, the test verifies, for a given UI scale, that the rendered text is `Check` when launching the dialog.

Jose Pereda has updated the pull request incrementally with one additional commit since the last revision:

  Check that the alert exists

-------------

Changes:
  - all: https://git.openjdk.java.net/jfx/pull/369/files
  - new: https://git.openjdk.java.net/jfx/pull/369/files/149caa77..4d148175

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=369&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=369&range=00-01

  Stats: 6 lines in 1 file changed: 5 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jfx/pull/369.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/369/head:pull/369

PR: https://git.openjdk.java.net/jfx/pull/369