RFR: 8296621: Stage steals focus on scene change [v5]

[Thiago Milczarek Sayao]

> Simple fix to not requestFocus() on scene change.
> 
> The attached bug sample shows that the TextField focused on the scene remains focused when the scene comes back.

Thiago Milczarek Sayao has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 29 additional commits since the last revision:

 - Use utility class.
 - Merge branch 'master' into 8296621_focus_stealing
 - Merge branch 'openjdk:master' into master
 - Add new line
 - Use JUnit 5
 - Add test
 - 8296621 - Stage steals focus on scene change
 - Merge branch 'openjdk:master' into master
 - Merge branch 'openjdk:master' into master
 - Merge branch 'openjdk:master' into master
 - ... and 19 more: https://git.openjdk.org/jfx/compare/7ef6332d...8ce83fde

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

Changes:
  - all: https://git.openjdk.org/jfx/pull/940/files
  - new: https://git.openjdk.org/jfx/pull/940/files/39d74209..8ce83fde

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=940&range=04
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=940&range=03-04

  Stats: 15933 lines in 1104 files changed: 6152 ins; 5286 del; 4495 mod
  Patch: https://git.openjdk.org/jfx/pull/940.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/940/head:pull/940

PR: https://git.openjdk.org/jfx/pull/940