move Filament headers to own directory under iOS/macOS

macos/include/filament/Engine.h

@@ -513,6 +513,14 @@ public:
      */
     size_t getMaxAutomaticInstances() const noexcept;
 
+    /**
+     * Queries the device and platform for instanced stereo rendering support.
+     *
+     * @return true if stereo rendering is supported, false otherwise
+     * @see View::setStereoscopicOptions
+     */
+    bool isStereoSupported() const noexcept;
+
     /**
      * @return EntityManager used by filament
      */