RFR: 8311895: CSS Transitions [v8]

[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"/>
> 
> ### Limitations
> This implementation supports both shorthand and longhand notations for the `transition` property. However, due to limitations of JavaFX CSS, mixing both notations doesn't work:
> 
> .button {
>     transition: -fx-background-color 1s;
>     transition-easing-function: linear;
> }
> 
> This issue should be addressed in a follow-up enhancement.

Michael Strauß has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 42 commits:

 - Merge branch 'master' into feature/css-transitions
 - Added documentation
 - Review changes
 - Review changes
 - Make interpolator fields final
 - Review changes
 - Make TransitionEvent final
 - Removed test
 - Removed trailing whitespace
 - Added manual test application
 - ... and 32 more: https://git.openjdk.org/jfx/compare/9b93c962...035fe5ca

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

Changes: https://git.openjdk.org/jfx/pull/870/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=870&range=07
  Stats: 4318 lines in 41 files changed: 4282 ins; 1 del; 35 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