[BUGFIX] filemetadata: differenciate between file types

filemetadata provides different set of meta data fields depending on
the file type.  This is now working as intended by referring to the
type field in the sys_file table.

Resolves: #52851
Releases: 6.2
Change-Id: I394a417af50312dbacfdfccbcbe2730866e9c5a1
Reviewed-on: https://review.typo3.org/25035
Reviewed-by: Steffen Ritter
Tested-by: Steffen Ritter