RFR: 8361379: [macos] Refactor accessibility code to retrieve attribute by name [v2]

[Alexander Zuev]

> - Copyright year update;
> - Introduce new function requestNodeAttribute and refactor code to use it;
> - Fix some typos;
> - Enable new code to handle TabPages since TabGroup was implemented;

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

  Reverting the curly bracket placement

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Changes:
  - all: https://git.openjdk.org/jfx/pull/1840/files
  - new: https://git.openjdk.org/jfx/pull/1840/files/92c74cbf..9bee13ac

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1840&range=01
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1840&range=00-01

  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jfx/pull/1840.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1840/head:pull/1840

PR: https://git.openjdk.org/jfx/pull/1840