[BUGFIX] Show active bed texture when bed model overlaps

When bed models are too large they are automatically hidden when another bed is added to avoid awkward spacing between beds/overlaps.
This also results in the bed texture being hidden and falling back to the default "translucent" grid view.

This bugfix changes the behavior to show the bed texture on the active bed even when the model is hidden which should be save
as the texture is always scaled to the bed size.

Original bug report: prusa3d#13791

src/slic3r/GUI/3DBed.cpp

@@ -407,14 +407,13 @@ void Bed3D::render_axes()
 void Bed3D::render_system(GLCanvas3D& canvas, const Transform3d& view_matrix, const Transform3d& projection_matrix, bool bottom, bool show_texture, bool is_active)
 {
     if (m_models_overlap && s_multiple_beds.get_number_of_beds() + int(s_multiple_beds.should_show_next_bed()) > 1) {
-        render_default(bottom, false, show_texture, view_matrix, projection_matrix);
-        return;
-    }
-
-    if (!bottom)
+        if (!is_active)
+            render_default(bottom, false, show_texture, view_matrix, projection_matrix);
+    } else if (!bottom) {
         render_model(view_matrix, projection_matrix);
+    }
 
-    if (show_texture)
+    if (show_texture && is_active)
         render_texture(bottom, canvas, view_matrix, projection_matrix, is_active);
     else if (bottom)
         render_contour(view_matrix, projection_matrix);