Add cue behavior for m3u files, too

[MickL]

The following files are scraped fine:

• game (track 1).bin
• game (track 2).bin
• game.cue

It will generate one entry for game.cue and skip the bin files. The exact same behavior should be integrated when using m3u files to connect multiple disks as described in the documentation:

• game (disc 1).bin
• game (disc 2).bin
• game (disc 1).CD1
• game (disc 2).CD2
• game.m3u

while game.m3u is just a simple list of the cue files (which have been renamed):

game (disc 1).CD1
game (disc 2).CD2

Current behavior:
Scraper does not find a cue file and will create an entry for each bin file. Also it will create no entry for the m3u file.

Desired behavior

• Find m3u files and use file-list as cue files
• Generate a single entry for m3u file
• Generate no entry for bin files

Link to Retropie Documentation on using M3U playlist for Multi-disc Games