Cleanup: Manifold Boolean: Change order of mesh construction

This patch swap position attribute initialization and edge construction
of boolean result. Logic is what both of these steps are last, all
future code do not build mesh topology but only maintain user
attributes. So at this point mesh already must be valid. But future
change of edge calculation (#132492) code will requer this mesh
validation to be done as part of the step. So when edges will be
calculated mesh must already be built, valid and contains position
attribute.

Pull Request: https://projects.blender.org/blender/blender/pulls/146229

source/blender/geometry/intern/mesh_boolean_manifold.cc

@@ -1824,13 +1824,6 @@ static Mesh *meshgl_to_mesh(MeshGL &mgl,
     });
   }
 
-  {
-#  ifdef DEBUG_TIME
-    timeit::ScopedTimer timer_e("calculating edges");
-#  endif
-    bke::mesh_calc_edges(*mesh, false, false);
-  }
-
   /* Set the vertex positions, using implicit sharing to avoid copying any data. */
   {
 #  ifdef DEBUG_TIME
@@ -1845,6 +1838,15 @@ static Mesh *meshgl_to_mesh(MeshGL &mgl,
     sharing_info->remove_user_and_delete_if_last();
   }
 
+  {
+#  ifdef DEBUG_TIME
+    timeit::ScopedTimer timer_e("calculating edges");
+#  endif
+    bke::mesh_calc_edges(*mesh, false, false);
+  }
+
+  BLI_assert(BKE_mesh_is_valid(mesh));
+
   OutToInMaps out_to_in(&ma, joined_mesh, mesh, &mesh_offsets);
 
   {