Check user permissions to determine if "Reopen" should be displayed on Closed MR Widget

Right now on Closed Merge requests, the Closed MR Widget shows the action "Reopen" any time the user is authenticated.

If the authenticated user cannot perform the Reopen action (e.g. if they are not a part of the project), clicking this widget action results in an error message from the server.

We should add a check to this widget action to determine if it should be shown to the authenticated user.

(Unauthenticated users do not see this action in the widget controls at all)