Show keybindings in refactor menu

[mjbvz]

Repo

1. Create a keybinding for extract constant:

	{
		"key": "shift+ctrl+e",
		"command": "editor.action.refactor",
		"args": {
			"kind": "refactor.extract.constant",
			"preferred": true
		}
	}

2. Open a js file:

   const a = 1 + 2;

3. Select 1 + 2 and click on lightbulb

Feature Request

Show the keybinding (shift+ctrl+e) for the extract to constant refactoring the lightbulb menu

[mjbvz]

For verifying this:

1. Make sure that the most specific keybinding is shown if multiple could be used
2. Also check that source actions (like organize imports) have keybindings shown in the source menu