[FEATURE] Support path prefixing in Media type ViewHelpers

This makes the ViewHelpers ideally compatible with TCA fields type "group" internalType "file" - when combined with an "uploadfolder" in TCA the new "path" argument is perfectly suited to contain that "uploadfolder".

Example:

TCA field: "videos" type group internalType file allowed mp4,ogg uploadfolder uploads/tx_myext maxitems 10. Results in CSV file1.ext,file2.ext,file3.ext etc.
ViewHelper call: <v:media.video path="uploads/tx_myext" src="{record.videos}" … />