[TASK] Add tests to GraphicalFunctions getImageScale

This change adds more examples to getImageScale
to have a good test bed in place before we move
code around for v13.

Resolves: #102026
Releases: main, 12.4
Change-Id: I82bfa00fb8f8342270505071d161de2462b782ea
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/81189


Reviewed-by: Benjamin Franzke <ben@bnf.dev>
Tested-by: Benjamin Franzke <ben@bnf.dev>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>