audio_in/out_system: Pass Initialize members by value where applicable

applet_resource_user_id isn't actually modified and is just assigned to
a member variable, so this doesn't need to be a mutable reference.

Similarly, the device name itself isn't modified and is only moved. We
pass by value here, since we can still perform the move, but eliminate a
sneaky set of calls that can unintentionally destroy the original
string. Given how nested the calls are, it's good to get rid of this
potential vector for a use-after-move bug.

src/audio_core/in/audio_in_system.cpp

@@ -56,7 +56,7 @@ Result System::IsConfigValid(const std::string_view device_name,
     return ResultSuccess;
 }
 
-Result System::Initialize(std::string& device_name, const AudioInParameter& in_params,
+Result System::Initialize(std::string device_name, const AudioInParameter& in_params,
                           const u32 handle_, const u64 applet_resource_user_id_) {
     auto result{IsConfigValid(device_name, in_params)};
     if (result.IsError()) {

src/audio_core/in/audio_in_system.h

@@ -97,7 +97,7 @@ public:
      * @param applet_resource_user_id - Unused.
      * @return Result code.
      */
-    Result Initialize(std::string& device_name, const AudioInParameter& in_params, u32 handle,
+    Result Initialize(std::string device_name, const AudioInParameter& in_params, u32 handle,
                       u64 applet_resource_user_id);
 
     /**