RFR: 8350316: Create implementation of NSAccessibilityProgressIndicator protocol [v2]

[Alexander Zuev]

> Initial implementation. In order to implement progress indicator the group accessibility protocol has to be implemented too so this is also a fix for 8351773. There are commented out sections that can be used to verify the functionality of the code since it has to behave exactly in the same way as the code without the fix. After review is done i will remove the debug output.

Alexander Zuev has updated the pull request incrementally with one additional commit since the last revision:

  - Added newlines where they were missing;
  - Removed ebug output;
  - Added comment mentioning that JFXProgressIndicatorAccessibility serves both ProgressBar and ProgressIndicator controls.

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Changes:
  - all: https://git.openjdk.org/jfx/pull/1796/files
  - new: https://git.openjdk.org/jfx/pull/1796/files/ce8dc77d..94bf9a1a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1796&range=01
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1796&range=00-01

  Stats: 14 lines in 3 files changed: 6 ins; 5 del; 3 mod
  Patch: https://git.openjdk.org/jfx/pull/1796.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1796/head:pull/1796

PR: https://git.openjdk.org/jfx/pull/1796