tlc: FindOutcome::Panelize opens the ExternalPanelize dialog

Previously FindOutcome::Panelize just printed 'not yet implemented'.
Now it opens the ExternalPanelize dialog so the user can type the
command, matching the F9→Command→External panelize flow.

Tests: 1486 passing (was 1486). No regression.

local/recipes/tui/tlc/source/src/filemanager/dialog_ops.rs

@@ -792,9 +792,7 @@ impl FileManager {
                     .set_message(format!("cd {}", dir.display()));
             }
             FindOutcome::Panelize => {
-                self.status.set_message(
-                    "Panelize: not yet implemented in current build".to_string(),
-                );
+                self.dialog = Some(DialogState::ExternalPanelize(Box::default()));
             }
             FindOutcome::ExternalPanelize(paths) => {
                 let mut paths = paths;