Add cluster common attributes

[kamiazya]

What was a problem

It was not possible to give common attributes to Node, Edge and Graph objects under the cluster.

How this PR fixes the problem

const Example: FC = () => (
  <Digraph
    dpi={150}
    rankdir="TB"
    edge={{
      color: 'blue',
      fontcolor: 'blue',
    }}
    node={{
      shape: 'none',
    }}
  />
);

Check lists (check x in [ ] of list items)

• Test passed
• Coding style (indentation, etc)