[BUGFIX] No content in workspace preview when using select.selectFields

The TypoScript property select.selectFields does not consider workspaces
in the frontend rendering process.

Taking the results from #29783 into account.

Change-Id: I6b2b68ed03163e9e0d7dd281aafea8af67fec224
Resolves: #17284
Releases: 4.6, 4.5, 4.4
Reviewed-on: http://review.typo3.org/4950
Reviewed-by: Oliver Hader
Reviewed-by: Wouter Wolters
Reviewed-by: Stefan Neufeind
Reviewed-by: Susanne Moog
Tested-by: Susanne Moog
Reviewed-by: Steffen Ritter
Tested-by: Steffen Ritter