This feature was originally exclusive to the previous iteration of
DolphinQt (the one that was the reason for the current iteration
being named DolphinQt2 initially).
https://bugs.dolphin-emu.org/issues/8949
The difference between Dolphin's game IDs and GameTDB's game IDs
is that GameTDB uses four characters for non-disc titles, whereas
Dolphin uses six characters for all titles.
This fixes:
- TitleDatabase considering Datel discs to be NHL Hitz 2002
- Gecko code downloading not working for discs with IDs starting with P
- Cover downloading mixing up discs with channels (e.g. Mario Kart Wii
and Mario Kart Channel) and making extra HTTP requests. (Android was
actually doing a better job at this than DolphinQt!)
Deduplicates code, and gets rid of some problems the old code had
(such as: bad performance when calling native functions, only one
disc showing up for multi-disc games, Wii banners being low-res,
unnecessarily much effort being needed for adding more metadata).
