RFR: 8368972: Create implementation of menu bar accessibility component [v5]

[Alexander Zuev]

> Create the accessibility peer for menu bar component also fix the problem when with the voiceover is on the <Ctrl>-F10 is pressed the name of the selected menu is not announced.

Alexander Zuev 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 nine additional commits since the last revision:

 - Merge remote-tracking branch 'origin/master' into JDK-8368972
 - Merge pull request #22 from openjdk/master
   
   Merge
 - Cover the case when menu item has children but it does not respond to the accessibilityValue selector;
 - Caching children list;
   Use nil instead of NULL;
 - Restore CHECK_MENU_ITEM binding
 - Fixing wrong copyright year
 - Fixing the assignment;
   Fixing the top level manu titles;
 - Fixed typo
 - 8368972: Create implementation of menu bar accessibility component
   
   Create a menu bar component accessibility peer and wire it to the component

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Changes:
  - all: https://git.openjdk.org/jfx/pull/1927/files
  - new: https://git.openjdk.org/jfx/pull/1927/files/7e83d9bd..aca3061f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1927&range=04
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1927&range=03-04

  Stats: 691 lines in 51 files changed: 555 ins; 40 del; 96 mod
  Patch: https://git.openjdk.org/jfx/pull/1927.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1927/head:pull/1927

PR: https://git.openjdk.org/jfx/pull/1927