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/nvdrv/nvdrv.h

@@ -100,7 +100,7 @@ struct EventInterface {
 
 class Module final {
 public:
-    Module(Core::System& system);
+    explicit Module(Core::System& system_);
     ~Module();
 
     /// Returns a pointer to one of the available devices, identified by its name.