Config: Port remaining Core settings to new config system (the rest).

[AdmiralCurtiss]

Depends on #10354.

I've put the Dual Core and MMU flags into the Core::System class, because they're accessed from quite a few locations, need to be fast to access, and can never change at game runtime anyway. If someone can think of a better place or solution, be my guest, but I think this works.

After this the only config read/write code not directly in the new config system is the remaining few GameINI and Netplay initialization things in BootManager.cpp. There's also a few settings left in the old config system that, apparently, never had a corresponding INI key and thus never persisted across sessions -- we probably need to decide on a case-by-case basis what we want to do with those. Same goes for the running game metadata that's stored in there. But hey, almost done now!

[dolphin-emu-bot]

FifoCI detected that this change impacts graphical rendering. Here are the behavior differences detected by the system:

• DKCR-Char on mvk-osx-m1: diff
• DKCR-fast-depth on mvk-osx-m1: diff
• ea-pink on mvk-osx-m1: diff
• inverted-depth-range on mvk-osx-m1: diff
• mp3-bloom on mvk-osx-m1: diff
• rs2-glass on mvk-osx-m1: diff
• rs2-skybox on mvk-osx-m1: diff
• spyro-bloom on mvk-osx-m1: diff
• ssbb-mod-lloyd on mvk-osx-m1: diff

_{^{automated-fifoci-reporter}}