<AWT Dev> RFR: 8256110: Create implementation for NSAccessibilityStepper protocol [v3]

[Alexander Zuev]

> 8256110: Create implementation for NSAccessibilityStepper protocol

Alexander Zuev has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains three commits:

 - Code cleanup
 - Fixed small glitch in new code.
 - 8256110: Create implementation for NSAccessibilityStepper protocol
   
   Initial implementation. Also i have moved AccessibilityAction code into
   the common layer so it can be easier accessible from other Action
   related components without much duplication.

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Changes: https://git.openjdk.java.net/jdk/pull/2092/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2092&range=02
  Stats: 131 lines in 5 files changed: 114 ins; 15 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2092.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2092/head:pull/2092

PR: https://git.openjdk.java.net/jdk/pull/2092