nn_acp: Implement ACPGetOlvAccesskey + code clean up

Added ACPGetOlvAccesskey() which is used by Super Mario Maker

iosu acp, nn_acp and nn_save all cross talk with each other and are mostly legacy code. Modernized it a tiny bit and moved functions to where they should be. A larger refactor should be done in the future but for now this works ok

src/Cafe/CafeSystem.cpp

@@ -530,6 +530,7 @@ namespace CafeSystem
 	{
 		// entries in this list are ordered by initialization order. Shutdown in reverse order
 		iosu::kernel::GetModule(),
+		iosu::acp::GetModule(),
 		iosu::fpd::GetModule(),
 		iosu::pdm::GetModule(),
 	};