Multi-disc support

[fraganator]

Add an option for extracting and caching all discs in a multi-disc game. Would allow quick disc swapping within emulator. Also investigate m3u support.

Things to consider:

• Treat multi-discs as a single cache entry (single lastplayed time, all files removed when cleaning cache)?
• Update playtime for all discs in game when any disc played?
• If one disc removed from cache, remove others?
  • Player may want to launch a single disc
• Extraction progress needs to include all discs, and account for any discs already in cache
• Logic to determine if multi-disc game on launch (similar to https://forums.launchbox-app.com/topic/53290-m3u-playlist-feature-i-got-questions/?do=findComment&comment=337769)
• Additional game.ini files, one per disc, when launching game

[fraganator]

Also add support to launch individual ROM from any disc. Maybe as drop down selector for each disc where current filename title is.

[fraganator]

Info on determining when LB generates m3u files: https://forums.launchbox-app.com/topic/53394-new-m3u-generation-doesnt-appear-to-be-working/?do=findComment&comment=338833

User presses play on a game.
LaunchBox checks if the emulator supports M3U files. If box is checked continue, if not play the game as is.
LaunchBox checks if the game has any additional apps, If there is some continue, if not play the game as is.
LaunchBox checks that the game/app launched matches an app with a disc number. If it does, create a M3U file. If not play the game as is.
LaunchBox checks for any other additional applications that have a disc number associated and adds them to the M3U file.
Launchbox then saves the created M3U file in the temp folder as the games GUID (found in that platforms XAML). This GUID doesn't change and is different per platform to eliminate issues with saves conflicting in RA.
Launchbox then passes that M3U to the emulator.