runDialog: Trim input before processing

This way, whitespace-only (nonempty) input gets the same treatment of
not being added to the history (see previous commit), which seems nice.

Part of https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/3183.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1442>

js/ui/runDialog.js

@@ -178,6 +178,7 @@ class RunDialog extends ModalDialog.ModalDialog {
     }
 
     _run(input, inTerminal) {
+        input = input.trim();
         let command = input;
 
         if (input)