Large STEP imports: no more multi-minute hang, shared STEP text, cancel and progress (#925)

crates/engine/src/tests.rs

@@ -254,6 +254,7 @@ fn join_of_two_overlapping_rings_is_not_refused() {
 
 mod boolean_diagnostics;
 mod component_frames;
+mod large_step_import;
 mod loft_cut;
 mod mirror_planes;
 mod path_scope;