feat: add spot light shadows with a tilled buffer

destrum/assets_src/shaders/scene_data.glsl

@@ -39,6 +39,11 @@ layout (buffer_reference, scalar) readonly buffer SceneDataBuffer {
     float shadowNormalOffset;
     uint padding;
     mat4 lightViewProj;
+
+    // spot shadows
+    uint spotShadowAtlasId;
+    uint spotShadowTilesPerRow;
+    SpotShadow spotShadows[MAX_SPOT_SHADOWS];
 } sceneDataBuffer;
 
 #endif // SCENE_DATA_GLSL