Adds focus: false to newly created modal dialogs

Without forcing focus false, the modal will not allow other modals to have focus for their inputs. This breaks tools like CKEditor.

From local testing, there are no negative side effects with not forcing focus on open.

src/rails_admin/remote-form.js

@@ -183,6 +183,7 @@ import * as bootstrap from "bootstrap";
         new bootstrap.Modal(widget.dialog[0], {
           keyboard: true,
           backdrop: true,
+          focus: false,
           show: true,
         }).show();
       }