RFR: 8359257: Create accessibility protocol for TabGroup component

[Alexander Zuev]

Create implementation of the TabGroup protocol and assign it to TAB_PANE and PAGINATION roles.

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Commit messages:
 - 8359257: Create accessibility protocol for TabGroup component

Changes: https://git.openjdk.org/jfx/pull/1823/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1823&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8359257
  Stats: 113 lines in 3 files changed: 111 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jfx/pull/1823.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1823/head:pull/1823

PR: https://git.openjdk.org/jfx/pull/1823