Clip the organic supports outside bed (#8195)

Clip the organic supports outside bed. (SoftFever/OrcaSlicer#7922)

(cherry picked from commit bambulab/BambuStudio@2c6a6ae5f4)

Co-authored-by: Arthur <arthur.tang@bambulab.com>
Co-authored-by: SoftFever <softfeverever@gmail.com>

src/libslic3r/Support/TreeModelVolumes.hpp

@@ -167,6 +167,8 @@ public:
             this->ceilRadius(radius + m_current_min_xy_dist_delta) - m_current_min_xy_dist_delta;
     }
 
+    Polygon m_bed_area;
+
 private:
     // Caching polygons for a range of layers.
     class LayerPolygonCache {