[TASK] Improve type annotations for ImageInfo

Also streamline some comments.

Resolves: #101988
Releases: main
Change-Id: Ia1a592dd58c950a48c37f6b8fa80168a22a1ce41
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/81128


Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Thomas Hohn <tho@gyldendal.dk>
Reviewed-by: Andreas Nedbal <andy@pixelde.su>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Andreas Nedbal <andy@pixelde.su>
Tested-by: Thomas Hohn <tho@gyldendal.dk>