loader: Make the Load() function take a process as a regular reference, not a SharedPtr

A process should never require being reference counted in this
situation. If the handle to a process is freed before this function is
called, it's definitely a bug with our lifetime management, so we can
put the requirement in place for the API that the process must be a
valid instance.

src/core/loader/nca.cpp

@@ -30,7 +30,7 @@ FileType AppLoader_NCA::IdentifyType(const FileSys::VirtualFile& file) {
     return FileType::Error;
 }
 
-ResultStatus AppLoader_NCA::Load(Kernel::SharedPtr<Kernel::Process>& process) {
+ResultStatus AppLoader_NCA::Load(Kernel::Process& process) {
     if (is_loaded) {
         return ResultStatus::ErrorAlreadyLoaded;
     }