WiiNetConfig: Eliminate usages of the global system accessor

[lioncash]

We can pass in the existing system instance from the ncd/manage instance.

[AdmiralCurtiss]

In theory these could just take memory instead, since that's already in scope at the call site. YMMV though.

[lioncash]

That's even better; it lets us remove the System.h include, since we already have Memmap.h included.

Switched over to that instead.

[dolphin-ci]

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

• bk-tev on mvk-osx-m1: diff
• burnout2-vehicletextures on mvk-osx-m1: failed to render
• djhero2-blend on mvk-osx-m1: diff
• fishing-resort-map on mvk-osx-m1: diff
• jb-shadow on mvk-osx-m1: diff
• kirby-logicop on mvk-osx-m1: diff
• lm-mario-portrait on mvk-osx-m1: diff
• major-minor on mvk-osx-m1: diff
• mario-golf-oob on mvk-osx-m1: diff
• mkdd-babypark on mvk-osx-m1: diff
• mkw-bridge on mvk-osx-m1: diff
• mkw-flags on mvk-osx-m1: diff
• mmx-light on mvk-osx-m1: diff
• mp2-scanner on mvk-osx-m1: diff
• mp3-bloom on mvk-osx-m1: diff
• rs3-skybox2 on mvk-osx-m1: diff
• smg-marioeyes on mvk-osx-m1: diff
• smg-mmg on mvk-osx-m1: diff
• smg-roar on mvk-osx-m1: diff
• sms-water on mvk-osx-m1: diff
• sonic-riders-blur on mvk-osx-m1: diff
• sonic-riders-zg-4p on mvk-osx-m1: diff
• tp-skin on mvk-osx-m1: diff
• custom-brawl-char on mtl-osx-m1: diff
• metroid-visor on mtl-osx-m1: diff
• ssbb-mod-lloyd on mtl-osx-m1: diff
• vegas-party-depth on mtl-osx-m1: diff

_{^{automated-fifoci-reporter}}