Instead of just using "edl/" for the file format, report mkv_oc if it's
generated from ordered chapters, "cue/" if from .cue, "multi/" if it's
from EDL but only for adding separate streams, "dash/" if it's from EDL
but only using the DASH hack, and "edl/" for everything else.
The EDL variants are mostly special-cased to the variants the ytdl
wrapper usually generates.
This has no effect other than what the command.c file-format property
returns.