Requests to retrieve the ThumbnailUrl are not compatible with TYPO3 v9

[benjaminkott]

Call to undefined method TYPO3\CMS\Backend\Utility\BackendUtility::getThumbnailUrl()

[benjaminkott]

Created a backport for the TYPO3 Core of @NeoBlack file module patch to render thumbnails deferred, to avoid workarounds. This patch is non-breaking and only speeds up the file module.

Waiting for @bmack @ohader @susannemoog how to proceed.
https://review.typo3.org/c/Packages/TYPO3.CMS/+/60417