[TASK] Cache non existing classes

To prevent multiple retries when loading information about non existing
classes (e.g. caused by class_exists() calls) the cache is filled with
an empty string when a non existing class is detected.

With this information the class loader can return early and does not
need to run all expensive checks for determining the class file.

Releases: 6.2
Resolves: #53962
Change-Id: I3c7e750bcce8846aaee79ac2d04527be2e31fc16
Reviewed-on: https://review.typo3.org/25679
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel