Add a Delete Post front end method and interface component

[sunnymui]

Currently, you are unable to delete a post from the front end.

There is a method defined in backend\routes\postsRoutes.js to delete a post, just no frontend function in src\api\api.js to send a delete request or an interface component that lets admin users click to delete a post.

Adding this would be nice to so we could put the D in CRUD app.