RFR: 8372203: Piecewise linear easing function [v6]

[Michael Strauß]

> Implementation of the [linear](https://www.w3.org/TR/css-easing-2/#the-linear-easing-function) easing function, which is now widely supported by all browsers, but still missing in JavaFX.
> 
> It allows developers to approximate arbitrary easing functions with linear segments:
> 
> 
> linear(
>     /* Start to 1st bounce */
>     0, 0.063, 0.25, 0.563, 1 36.4%,
>     /* 1st to 2nd bounce */
>     0.812, 0.75, 0.813, 1 72.7%,
>     /* 2nd to 3rd bounce */
>     0.953, 0.938, 0.953, 1 90.9%,
>     /* 3rd bounce to end */
>     0.984, 1 100% 100%
>   )
> 
> 
> <img src="https://github.com/user-attachments/assets/73aac0d4-0185-47c5-8791-bdb247eb69c8" width="400"/>

Michael Strauß has updated the pull request incrementally with one additional commit since the last revision:

  need to have at least 2 control points

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

Changes:
  - all: https://git.openjdk.org/jfx/pull/1977/files
  - new: https://git.openjdk.org/jfx/pull/1977/files/bb537681..368efe34

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1977&range=05
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1977&range=04-05

  Stats: 26 lines in 4 files changed: 9 ins; 13 del; 4 mod
  Patch: https://git.openjdk.org/jfx/pull/1977.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1977/head:pull/1977

PR: https://git.openjdk.org/jfx/pull/1977