RFR: 8313424: JavaFX controls in the title bar [v22]

[Michael Strauß]

> Implementation of [`EXTENDED` stage style](https://gist.github.com/mstr2/0befc541ee7297b6db2865cc5e4dbd09).

Michael Strauß has updated the pull request incrementally with three additional commits since the last revision:

 - HeaderBar changes
 - EMPTY Dimension2D constant
 - use CsvSource in HeaderBarTest

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

Changes:
  - all: https://git.openjdk.org/jfx/pull/1605/files
  - new: https://git.openjdk.org/jfx/pull/1605/files/d1c388bf..8974c141

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1605&range=21
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1605&range=20-21

  Stats: 142 lines in 3 files changed: 8 ins; 68 del; 66 mod
  Patch: https://git.openjdk.org/jfx/pull/1605.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1605/head:pull/1605

PR: https://git.openjdk.org/jfx/pull/1605