REFEDIT: Edit Reference dialog and unique names for xref objects

REFEDIT opens a dialog after the pick: the nesting chain as chips with a
preview of the chosen definition, all objects or picking them in the
drawing, attribute definitions (offered only when the definition has
them), locking objects outside the working set and unique names for an
external reference's named objects. The settings are remembered.

With unique names an xref's dependent layers, linetypes, text styles and
blocks are checked out as $N$NAME records of their own; without, under
the plain name, sharing a host record of that name. Save writes them back
under the reference's names, and the records made for the session are
removed when it closes. -REFEDIT uses the remembered settings.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/ui/window/mod.rs

@@ -29,6 +29,7 @@ pub mod plot;
 pub mod plugin_manager;
 pub mod print_all;
 pub mod recovery;
+pub mod refedit_dialog;
 pub mod sheet_set;
 pub mod shortcuts;
 pub mod update_notice;