video_core: Refactor GPU interface (#7272)

* video_core: Refactor GPU interface

* citra_qt: Better debug widget lifetime

src/core/core.h

@@ -58,9 +58,13 @@ class Backend;
 
 namespace VideoCore {
 class CustomTexManager;
-class RendererBase;
+class GPU;
 } // namespace VideoCore
 
+namespace Pica {
+class DebugContext;
+}
+
 namespace Loader {
 class AppLoader;
 }
@@ -217,7 +221,7 @@ public:
         return *dsp_core;
     }
 
-    [[nodiscard]] VideoCore::RendererBase& Renderer();
+    [[nodiscard]] VideoCore::GPU& GPU();
 
     /**
      * Gets a reference to the service manager.
@@ -384,6 +388,8 @@ private:
     /// Telemetry session for this emulation session
     std::unique_ptr<Core::TelemetrySession> telemetry_session;
 
+    std::unique_ptr<VideoCore::GPU> gpu;
+
     /// Service manager
     std::unique_ptr<Service::SM::ServiceManager> service_manager;