core/loader: Remove dependencies on the global system instance

Now all that remains is:

18 instances in file_sys code
14 instances in GDB stub code (this can be tossed wholesale)
4 instances in HLE code
2 instances in settings code.

src/core/loader/kip.cpp

@@ -43,7 +43,8 @@ FileType AppLoader_KIP::GetFileType() const {
                                                                          : FileType::Error;
 }
 
-AppLoader::LoadResult AppLoader_KIP::Load(Kernel::Process& process) {
+AppLoader::LoadResult AppLoader_KIP::Load(Kernel::Process& process,
+                                          [[maybe_unused]] Core::System& system) {
     if (is_loaded) {
         return {ResultStatus::ErrorAlreadyLoaded, {}};
     }