RFR: 8267565: Support "@3x" and greater high-density image naming convention [v2]

[drmarmac]

> This PR extends the range of hi-res images that are loaded via naming convention, now including scale factors higher than `@2x`. 
> Supporting these is already being [recommended](https://developer.apple.com/design/human-interface-guidelines/images#Best-practices) for some platforms.
> 
> I tested this manually on Windows with "300%" UI scale factor, and verified `@2x` still works on macOS.

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

  Change name2x to nameScaled

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

Changes:
  - all: https://git.openjdk.org/jfx/pull/1429/files
  - new: https://git.openjdk.org/jfx/pull/1429/files/4c2b03e0..536143fc

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1429&range=01
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1429&range=00-01

  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jfx/pull/1429.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1429/head:pull/1429

PR: https://git.openjdk.org/jfx/pull/1429