[TASK] Adds fileReferenceUid to content rendering

FrontendContentAdapterService saves the file uid but not the
file reference uid.

This commits adds the file reference uid.

Change-Id: I5af09521d5dadc194ec567aec24792def370aedc
Resolves: #49535
Releases: 6.2
Reviewed-on: https://review.typo3.org/21759
Reviewed-by: Andreas Wolf
Reviewed-by: Lars Peipmann
Reviewed-by: Steffen Ritter
Reviewed-by: Stefan Neufeind
Reviewed-by: Markus Klein
Tested-by: Markus Klein
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters