RFR: 8313424: JavaFX controls in the title bar [v27]

[Michael Strauß]

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

Michael Strauß has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 34 commits:

 - Merge branch 'master' into feature/extended-window
 - Merge branch 'master' into feature/extended-window
 - add system menu documentation
 - WindowControlsOverlay snapping
 - HeaderBar javadoc change
 - refactor performWindowDrag
 - HeaderBar changes
 - EMPTY Dimension2D constant
 - use CsvSource in HeaderBarTest
 - stylistic changes
 - ... and 24 more: https://git.openjdk.org/jfx/compare/d0011b21...65f095ef

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Changes: https://git.openjdk.org/jfx/pull/1605/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1605&range=26
  Stats: 4882 lines in 61 files changed: 4368 ins; 409 del; 105 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