Fix friend declaration in IteratorFacade

This MR fixes a friend class declaration. It should be struct or just friend due to the provious class definition.

assigned to @carsten.graeser

added 1 commit

• c64d163a - [cleanup] Don't use friend forward declaration

Compare with previous version

You're faster than me, I didn't find time to push this so far. Now also the other occasions are fixed.

enabled an automatic merge when the pipeline for c64d163a succeeds

merged

mentioned in commit 847a62c8