RFR: 8290844: Add Skin.install() method [v13]

[Andy Goryachev]

> - added Skin.install()
> - javadoc changes for Skinnable.setSkin(Skin)

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 26 additional commits since the last revision:

 - Merge remote-tracking branch 'origin/master' into 8290844.skin.install
 - 8290844: review comments
 - Merge remote-tracking branch 'origin/master' into 8290844.skin.install
 - 8290844: javadoc
 - Merge remote-tracking branch 'origin/master' into 8290844.skin.install
 - 8290844: javadoc
 - Merge branch 'openjdk:master' into 8290844.skin.install
 - 8290844: unit tests
 - Merge remote-tracking branch 'origin/master' into 8290844.skin.install
 - 8290844: review comments
 - ... and 16 more: https://git.openjdk.org/jfx/compare/f2250911...4aaf422b

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

Changes:
  - all: https://git.openjdk.org/jfx/pull/845/files
  - new: https://git.openjdk.org/jfx/pull/845/files/97ad66c0..4aaf422b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=845&range=12
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=845&range=11-12

  Stats: 15 lines in 5 files changed: 5 ins; 3 del; 7 mod
  Patch: https://git.openjdk.org/jfx/pull/845.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/845/head:pull/845

PR: https://git.openjdk.org/jfx/pull/845