Move controller creation to System class, switch shared_ptr to unique_ptr

src/core/host_interface.cpp

@@ -66,7 +66,6 @@ bool HostInterface::BootSystem(const char* filename, const char* state_filename)
     return false;
 
   m_paused = m_settings.start_paused;
-  ConnectControllers();
   UpdateSpeedLimiterState();
 
   if (state_filename && !LoadState(state_filename))
@@ -208,8 +207,6 @@ std::optional<std::vector<u8>> HostInterface::GetBIOSImage(ConsoleRegion region)
   return BIOS::LoadImageFromFile(m_settings.bios_path);
 }
 
-void HostInterface::ConnectControllers() {}
-
 void HostInterface::Throttle()
 {
   // Allow variance of up to 40ms either way.