RFR: 8294589: MenuBarSkin: memory leak when changing skin [v3]

[Andy Goryachev]

> Fixed memory leak by using weak listeners and making sure to undo everything that has been done to MenuBar/Skin in dispose().
> 
> This PR depends on a new internal class ListenerHelper, a replacement for LambdaMultiplePropertyChangeListenerHandler.
> See https://github.com/openjdk/jfx/pull/908

Andy Goryachev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 20 additional commits since the last revision:

 - 8294589: cleanup
 - 8294589: using listener helper
 - Merge branch '8294809.listener.helper' into 8294589.menubarskin.leak.listener.helper
 - 8294809: event handlers and filters
 - Merge branch '8294589.menubarskin.leak' into 8294589.menubarskin.leak.listener.helper
 - 8294589: unnecessary null checks
 - 8294589: unnecessary null checks
 - Merge branch '8294809.listener.helper' into 8294589.menubarskin.leak.listener.helper
 - 8294809: cleanup
 - 8294809: override
 - ... and 10 more: https://git.openjdk.org/jfx/compare/cb41158d...5e1cef12

-------------

Changes:
  - all: https://git.openjdk.org/jfx/pull/906/files
  - new: https://git.openjdk.org/jfx/pull/906/files/7824baa8..5e1cef12

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=906&range=02
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=906&range=01-02

  Stats: 1622 lines in 12 files changed: 1383 ins; 202 del; 37 mod
  Patch: https://git.openjdk.org/jfx/pull/906.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/906/head:pull/906

PR: https://git.openjdk.org/jfx/pull/906