sdvx: landscape mode (#277)

## Link to GitHub Issue, if one exists
n/a

## Description of change
Add `SDVX Landscape Mode` option, allowing you to play SDVX in landscape
monitor orientation, with black borders on left and right - similar to
how EAC does it. This is meant to be an alternative to what people do
today, which is launching in windowed mode.

By default, with just `-sdvxlandscape` enabled, EG will launch at
1920x1080 (transposed from the original 1080x1920 resolution).

It is possible to combine with `-forceres` to launch at higher
resolutions. At some point though, when rendering at large resolutions
past 1440p, at some point scaling may break due to #276.

Disabled on 32-bit SDVX since dx9 `CreateDeviceEx` call is required;
`CreateDevice` won't work. For the same reason this isn't being made a
generic option for museca/rb/etc. In theory you can supply
`-sdvxlandscape` to games like IIDX and play landscape games in portrait
mode, although again, scaling my break due to #276.

Also, add new options (bottomleft/right) for subscreen overlay position
so that they don't overlap with the main screen in landscape mode.

## Compiling
🙂

## Testing
Tested a couple versions of VW and EG.

src/spice2x/games/sdvx/sdvx.h

@@ -11,7 +11,9 @@ namespace games::sdvx {
     enum SdvxOverlayPosition {
         SDVX_OVERLAY_TOP,
         SDVX_OVERLAY_MIDDLE,
-        SDVX_OVERLAY_BOTTOM
+        SDVX_OVERLAY_BOTTOM,
+        SDVX_OVERLAY_BOTTOM_LEFT,
+        SDVX_OVERLAY_BOTTOM_RIGHT
     };
 
     // settings