Core/Movie: Refactor to class, move to System.

A bit of global state remains (the `header` in `BeginRecordingInput()`) due to unclear lifetime requirements.

Source/Core/Core/System.h

@@ -74,6 +74,10 @@ namespace MemoryInterface
 {
 class MemoryInterfaceManager;
 };
+namespace Movie
+{
+class MovieManager;
+}
 namespace PixelEngine
 {
 class PixelEngineManager;
@@ -161,6 +165,7 @@ public:
   Memory::MemoryManager& GetMemory() const;
   MemoryInterface::MemoryInterfaceManager& GetMemoryInterface() const;
   PowerPC::MMU& GetMMU() const;
+  Movie::MovieManager& GetMovie() const;
   PixelEngine::PixelEngineManager& GetPixelEngine() const;
   PixelShaderManager& GetPixelShaderManager() const;
   PowerPC::PowerPCManager& GetPowerPC() const;