RetroAchievements scan doesn't work when primary file is .m3u type

[retroNUC]

After the initial scan, it didn’t expand and scan within .m3u playlist files, which is likely what the default file is for multi-disc titles.

As an improvement, I’d suggest:

• Parsing the playlist file and scanning individual entries (relative or absolute path) to see if it matches a RA hash
• Also scanning files under Additional Applications to see if it matches an RA hash, and marking the main entry as ‘Has Achievements’ if so

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