* kubed.el (kubed-define-resource): Also generate
'kubed-RESOURCE-context-menu' function for each RESOURCE,
and add it to 'context-menu-functions' in list buffers.
* kubed.el (tramp-kubernetes-namespace): Remove declaration.
(kubed--static-if): New macro. Compatibility definition of
'static-if' from Emacs 30.
(kubed-pods-dired, kubed-pods-shell): Do not rely on
explicit Kubernetes namespace in remote file name syntax in
Emacs versions earlier than 31.
(kubed-define-resource): Use 'emacsclient-program-name' only
in Emacs 30 or later.