service: Eliminate usages of the global system instance

Completely removes all usages of the global system instance within the
services code by passing in the using system instance to the services.

src/core/hle/service/nim/nim.h

@@ -4,14 +4,14 @@
 
 #pragma once
 
-namespace Service::SM {
-class ServiceManager;
-}
-
 namespace Core {
 class System;
 }
 
+namespace Service::SM {
+class ServiceManager;
+}
+
 namespace Service::NIM {
 
 void InstallInterfaces(SM::ServiceManager& sm, Core::System& system);