drs: rgb camera hook (#524)

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

## Description of change
Add plug&play hooks for RGB camera in DRS.

## Testing
Seems to work with my crappy Logitech C270

Camera options (brightness etc) seem to work in test menu as well).

Tested by another user with realsense camera + logitech camera, both
cams were detected correctly.

src/spice2x/launcher/options.cpp

@@ -2219,6 +2219,17 @@ static const std::vector<OptionDefinition> OPTION_DEFINITIONS = {
         .game_name = "DANCERUSH",
         .category = "Game Options",
     },
+    {
+        // DRSRGBCameraHook
+        .title = "DRS RGB Camera Hook",
+        .name = "drsrgbcamhook",
+        .desc = "Hook into the RGB camera detection and attempt to use your own non-official webcam. "
+            "Not every webcam will be compatible with this; YMMV.\n\n"
+            "Note: this is NOT for the motion camera - you still need a real RealSense camera for that!",
+        .type = OptionType::Bool,
+        .game_name = "DANCERUSH",
+        .category = "Game Options",
+    },
     {
         // spice2x_IIDXNativeTouch
         .title = "IIDX Native Touch Handling",