[Feature Request] Display existing children of work item being decomposed

[psjeeper]

It would be very helpful to display a list of existing work items that are part of the hierarchy. The use case is that you want to come back to a user story and continue decomposition and it has existing linked children. Having this list would alleviate any duplicate work items being created along with enabling the ability to continue work item decomposition at a later date. If you choose to implement this the existing work items should not be editable through this extension. Here is an example of how I would see the UI representing this change. Note, the work items without <> and "X" controls are those which are existing. All actions should be disabled for these.