chore(deps): extract stylesheet from deprecated react-dd-menu (#3489)

* chore(deps): extract stylesheet from deprecated react-dd-menu

* chore(deps): remove react-dd-menu

NOTICE

@@ -1,2 +1,7 @@
 swagger-editor
 Copyright 2020-2021 SmartBear Software Inc.
+
+react-dd-menu
+Copyright (c) 2015 Mikkel Laursen
+Specific Sass Cascading Style Sheet in `_dropdown-menu.less` (the file) were originally created under MIT license in https://github.com/mlaursen/react-dd-menu repository.
+Specific Sass Cascading Style Sheet have been copied into this project and modified. All modifications are licensed under Apache 2.0 License.

package.json

@@ -79,7 +79,6 @@
     "react": "=17.0.2",
     "react-ace": "^4.1.6",
     "react-addons-css-transition-group": "^15.4.2",
-    "react-dd-menu": "^2.0.0",
     "react-dom": "=17.0.2",
     "react-dropzone": "^12.0.4",
     "react-immutable-proptypes": "^2.1.0",