Support bookmarking Kubernetes resource buffers

Support bookmarking Kubernetes resource buffers

* kubed.el (kubed-display-resource-info): New variable.
(kubed-display-resource-revert)
(kubed-display-resource-in-buffer)
(kubed-display-resource-handle-bookmark)
(kubed-display-resource-make-bookmark): New functions.
(kubed-display-resource-mode): New minor mode, enabled in
buffers that display resources in YAML format.
(kubed-define-resource): Use 'kubed-display-resource-in-buffer'
in definition of generated 'kubed-RESOURCE-description-buffer'.