Major cleanup: simplify and extend resource lists

Major cleanup: simplify and extend resource lists

This is a big refactor that does the following:

- Significantly simplify 'kubed-define-resource', use common
  type-generic code in runtime instead of generating duplicate code
  for each type.

- Support multiple list buffers with per-buffer namespace
  and context.

- Drop 'kubed-all-namespaces-mode', at least for now.