Fetches schema from server without caching to disk.  Caching / offline
operation will be added in a followup PR.

File format is recognised via simple file extension check.

Any "List" objects found will be expanded into their constituent
items, so single-element formats like json and jsonnet can use a
v1.List to capture multiple resource objects.

Basic skeleton.  Can evaluate jsonnet and show the output as yaml or
json .. and that's about it.