RFR: 8311895: CSS Transitions

[Michael Strauß]

Implementation of [CSS 
Transitions](https://gist.github.com/mstr2/c72f8c9faa87de14926978f517a6018a).

### Example

.button {
    -fx-background-color: dodgerblue;
}

.button:hover {
    -fx-background-color: red;
    -fx-scale-x: 1.1;
    -fx-scale-y: 1.1;

    transition: -fx-background-color 0.5s ease,
                -fx-scale-x 0.5s ease,
                -fx-scale-y 0.5s ease;
}

<img 
src="https://user-images.githubusercontent.com/43553916/184781143-0520fbfe-54bf-4b8d-93ac-834708e46500.gif";
 width="200"/>

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

Commit messages:
 - Removed test
 - Removed trailing whitespace
 - Added manual test application
 - Redundant transitions are discarded
 - Refactoring
 - Intern parsed property names
 - Start transitions only for showing nodes
 - Refactoring
 - Added documentation
 - Refactoring
 - ... and 25 more: https://git.openjdk.org/jfx/compare/5aad0406...9cdeb498

Changes: https://git.openjdk.org/jfx/pull/870/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=870&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8311895
  Stats: 4249 lines in 40 files changed: 4214 ins; 1 del; 34 mod
  Patch: https://git.openjdk.org/jfx/pull/870.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/870/head:pull/870

PR: https://git.openjdk.org/jfx/pull/870