Implement a minimized yaml editor view for gx files

See issue #3 first as that is a prerequisite to this feature request.

In some very high-latency situations we would like to be able to edit graphs in the UI without having to use the default visual graph. This would be similar to editing raw python or yaml. Issue #3 is a good first step, but I think we could do even better by having some kind of 'smart' or 'minimized' view of the yaml we are editing.

For example, imagine a text editor that just let you type in the name of the nodes you wanted to run and the editor would grab the node class from the backend registry and auto-populate which fields that particular node has (on-demand). The editor would figure out where in the chain of nodes this new node would need to be placed automatically. In this way, the yaml could be 'minimized' to just show the relevant information a user cares about.

Read issue #3 first, since it is identified as a prerequisite. Then examine the existing UI graph editor and the backend node registry to understand how gx YAML is represented and edited. Done means users can edit a minimized YAML view that resolves node classes, exposes fields on demand, and places new nodes in the chain automatically.