Feature: Allow additional action(s) for a node

[jsolaas]

We want to be able to add actions to nodes, i.e. when triggering an action on a node we want to open a separate page with more information.

• We need to handle the action trigger outside the diagram component
• We need to be able to only have the action available on some nodes
• The info on which nodes should show the action should not be in the current flow diagram prop

My proposal:

Add a render prop that should be used to render actions for a node. This can probably cause some issues with size etc that we need to figure out.

An alternative is to specify an action

interface Action {
  icon: string;
  onClick: (node: Node) => void;
  nodeType: NodeType;
}

but then we need to make sure we can implement that action for all nodes of a type.