Add option to not draw background -- for transparent videos

include/rive/artboard.hpp

diff --git a/include/rive/artboard.hpp b/include/rive/artboard.hpp
index c3afe0c..7b7533c 100644
--- a/include/rive/artboard.hpp
+++ b/include/rive/artboard.hpp
@@ -66,7 +66,7 @@
         void onDirty(ComponentDirt dirt) override;
 
         bool advance(double elapsedSeconds);
-        void draw(Renderer* renderer);
+        void draw(Renderer* renderer, bool drawBackground = true);
 
         CommandPath* clipPath() const { return m_ClipPath; }
         CommandPath* backgroundPath() const { return m_BackgroundPath; }

src/artboard.cpp

diff --git a/src/artboard.cpp b/src/artboard.cpp
index 395354b..0bbca01 100644
--- a/src/artboard.cpp
+++ b/src/artboard.cpp
@@ -452,7 +452,7 @@
     return updateComponents();
 }
 
-void Artboard::draw(Renderer* renderer)
+void Artboard::draw(Renderer* renderer, bool drawBackground)
 {
     renderer->save();
     if (clip())
@@ -467,9 +467,13 @@
         artboardTransform[5] = height() * originY();
         renderer->transform(artboardTransform);
     }
-    for (auto shapePaint : m_ShapePaints)
+
+    if (drawBackground)
     {
-        shapePaint->draw(renderer, m_BackgroundPath);
+        for (auto shapePaint : m_ShapePaints)
+        {
+            shapePaint->draw(renderer, m_BackgroundPath);
+        }
     }
 
     for (auto drawable = m_FirstDrawable; drawable != nullptr;