Refactor NDS and DSi to be objects (#1893)

* First crack at refactoring NDS and DSi into objects

- Remove all global/`static` variables in `NDS` and related classes
- Rely more on virtual dispatch when we need to pick methods at runtime
- Pass `NDS&` or `DSi&` to its constituent components where necessary
- Introduce some headers or move some definitions to break `#include` cycles

* Refactor the frontend to accommodate the core's changes

* Move up `SchedList`'s declaration

- Move it to before the components are initialized so the `map`s inside are initialized
- Fields in C++ are initialized in the order they're declared

* Fix a crash when allocating memory

* Fix JIT-free builds

* Fix GDB-free builds

* Fix Linux builds

- Explicitly qualify some member types in NDS, since they share the same name as their classes

* Remove an unnecessary template argument

- This was causing the build to fail on macOS

* Fix ARM and Android builds

* Rename `Constants.h` to `MemConstants.h`

* Add `NDS::IsRunning()`

* Use an `#include` guard instead of `#pragma once`

src/frontend/qt_sdl/ROMInfoDialog.h

@@ -29,17 +29,17 @@
 
 namespace Ui { class ROMInfoDialog; }
 class ROMInfoDialog;
-
+namespace melonDS::NDSCart { class CartCommon; }
 class ROMInfoDialog : public QDialog
 {
     Q_OBJECT
 
 public:
-    explicit ROMInfoDialog(QWidget* parent);
+    explicit ROMInfoDialog(QWidget* parent, const melonDS::NDSCart::CartCommon& rom);
     ~ROMInfoDialog();
 
     static ROMInfoDialog* currentDlg;
-    static ROMInfoDialog* openDlg(QWidget* parent)
+    static ROMInfoDialog* openDlg(QWidget* parent, const melonDS::NDSCart::CartCommon& rom)
     {
         if (currentDlg)
         {
@@ -47,7 +47,7 @@ public:
             return currentDlg;
         }
 
-        currentDlg = new ROMInfoDialog(parent);
+        currentDlg = new ROMInfoDialog(parent, rom);
         currentDlg->open();
         return currentDlg;
     }