Allow users to delete edges in the middle of a workflow

[NickOpenFn]

Right now, users are not able to the delete nodes/edges in the middle of workflows but we want to provide this level of flexibility for users. As a user, I should be able to select a node or an edge and delete it.

• When I delete a node (step), it should be removed from the workflow leaving other
• When I delete an edge, it should be removed but the upstream and downstream jobs
• If we have an orphaned step - one where a node/edge is deleted in the middle without being and , the workflow should run to the last job that is connected.

The implementation of #2008 covered a part of this fix but we need to decide how we want to handle the deleted nodes -- if they are considered a part of the workflow that can be added later in which case, we should make sure that when a user refreshes, the nodes/steps are not deleted.

We want to persist every orphan node and their downstream in the workflow.