[jdk11u-dev] RFR: 8264290: Create implementation for NSAccessibilityComponentGroup protocol peer

[Autumn Capasso]

This Backport is clean [JDK-8264290](https://bugs.openjdk.org/browse/JDK-8264290). Tested and built locally. Part of 28 part Accessibility series [JDK-8152350](https://bugs.openjdk.org/browse/JDK-8152350).

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Commit messages:
 - Backport 6c107fdff289cc553df12ee10b0c8002b84059b2
 - Backport 9d669c912d3977027f321a5e6b7f045ca2ce9482)

Changes: https://git.openjdk.org/jdk11u-dev/pull/1705/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1705&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8264290
  Stats: 509 lines in 8 files changed: 363 ins; 135 del; 11 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1705.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev pull/1705/head:pull/1705

PR: https://git.openjdk.org/jdk11u-dev/pull/1705