[jdk11u-dev] RFR: 8264304: Create implementation for NSAccessibilityToolbar protocol peer

[Autumn Capasso]

Clean backport [JDK-8264304](https://bugs.openjdk.org/browse/JDK-8264304). Part of 28 Accessibility backport https://bugs.openjdk.org/browse/JDK-8152350.

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Commit messages:
 - Backport 4d26f22b9adcf7cecca5316348ef670ac2dbc365
 - Backport 9d669c912d3977027f321a5e6b7f045ca2ce9482)

Changes: https://git.openjdk.org/jdk11u-dev/pull/1706/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1706&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8264304
  Stats: 190 lines in 4 files changed: 163 ins; 14 del; 13 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1706.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev pull/1706/head:pull/1706

PR: https://git.openjdk.org/jdk11u-dev/pull/1706