Add level hierarchy field to resources model for improved navigation

[agrogers]

With the growing number of resource records, it's increasingly difficult to locate specific resources within the system. Typically, it is useful to identify top-level parent resources and drill down into their children. The top-level resources can be identified by the absence of any parent resources.

Suggested solution:

• Provide UI filters to make it easy to list only top-level resources or to navigate the hierarchy.