RFR: 8090456: Focus Management [v3]

[Andy Goryachev]

> Public APIs for focus traversal and the focus traversal policy:
> 
> https://github.com/andy-goryachev-oracle/Test/blob/main/doc/FocusTraversal/FocusTraversal.md
> 
> This work is loosely based on the patch
> https://cr.openjdk.org/~jgiles/8061673/

Andy Goryachev has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains nine commits:

 - Merge remote-tracking branch 'origin/master' into 8090456.focus.traversal
 - Merge remote-tracking branch 'origin/master' into 8090456.focus.traversal
 - review comments
 - Merge remote-tracking branch 'origin/master' into 8090456.focus.traversal
 - review comments part 1
 - Merge remote-tracking branch 'origin/master' into 8090456.focus.traversal
 - Merge remote-tracking branch 'origin/master' into 8090456.focus.traversal
 - whitespace
 - 8090456: focus traversal

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Changes: https://git.openjdk.org/jfx/pull/1555/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1555&range=02
  Stats: 3656 lines in 57 files changed: 1603 ins; 1538 del; 515 mod
  Patch: https://git.openjdk.org/jfx/pull/1555.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1555/head:pull/1555

PR: https://git.openjdk.org/jfx/pull/1555