gitadora: allow a landscape monitor to display subscreen (#899)

## Link to GitHub Issue or related Pull Request, if one exists
#0

## Description of change
Arena Model's SMALL touch subscreen is a portrait (800x1280) panel -
however, it's common for people to set up a touch screen in landscape
orientation since IIDX/SDVX/popn all use landscape.

Add a new option, `-gdsublandscape`, which forces the subscreen to
launch at 1080p landscape. The image is rendered with black bars on the
sides. Touches will be unaligned initially; user needs to go into test
mode and recalibrate. In reality this option is just a short hand for
`-forceressub 1920,1080`.

Wire up `-forceressub` which previously didn't work for gitadora, so
that a resolution other than 1080p can be used in either orientation. In
other games `-forceressub` just forces the rendering resolution and
IIDX/SDVX/popn's game engine automatically stretches to fill... however
for gitadora it works differently since we want to keep the aspect ratio
of the original screen; it instead hijacks the back buffer and makes the
game draw to an intermediate buffer.

## Testing

src/spice2x/hooks/graphics/backends/d3d9/d3d9_gfdm.h

@@ -13,6 +13,34 @@ inline constexpr UINT GFDM_SMALL_HEIGHT = games::gitadora::ARENA_SUBSCREEN_HEIGH
 inline constexpr UINT GFDM_LOGICAL_HEAD_COUNT = 4;
 inline constexpr UINT GFDM_NATIVE_SMALL_SWAPCHAIN = 1;
 
+// Owns the portrait surface the game draws into while the SMALL head is scanned out at a
+// different resolution, and composes it onto the real head. Allocates nothing and reports
+// nothing until resolve() finds a head that is not the panel size.
+struct GfdmSmallHead {
+    GfdmSmallHead() = default;
+    ~GfdmSmallHead() { release(); }
+    GfdmSmallHead(const GfdmSmallHead &) = delete;
+    GfdmSmallHead &operator=(const GfdmSmallHead &) = delete;
+
+    // settled with the device, so it cannot change under the game mid-session
+    void resolve(const D3DPRESENT_PARAMETERS *logical_small_parameters);
+    bool scaled() const { return active; }
+
+    HRESULT backbuffer(IDirect3DDevice9 *device, IDirect3DSurface9 **out);
+    HRESULT compose(IDirect3DDevice9 *device);
+    void release();
+
+    // the game only ever sees the portrait size it asked for
+    void apply_logical_size(UINT *width, UINT *height) const;
+
+private:
+    bool active = false;
+    D3DFORMAT format = D3DFMT_X8R8G8B8;
+    D3DMULTISAMPLE_TYPE multisample = D3DMULTISAMPLE_NONE;
+    DWORD multisample_quality = 0;
+    IDirect3DSurface9 *surface = nullptr;
+};
+
 struct GfdmTwoHeadDeviceState {
     explicit GfdmTwoHeadDeviceState(
             D3DPRESENT_PARAMETERS *presentation_parameters,
@@ -41,6 +69,10 @@ struct GfdmTwoHeadDeviceState {
 };
 
 bool gfdm_two_head_exclusive();
+void gfdm_publish_two_head_parameters(
+        D3DPRESENT_PARAMETERS *logical_presentation_parameters,
+        D3DDISPLAYMODEEX *logical_fullscreen_display_modes,
+        const GfdmTwoHeadDeviceState &state);
 bool is_fake_subscreen_adapter(UINT adapter);
 void get_fake_subscreen_display_mode(UINT adapter, D3DDISPLAYMODE *mode);
 void get_fake_subscreen_display_mode_ex(UINT adapter, D3DDISPLAYMODEEX *mode);