Add menu bindings to new functions in image-dired.el

Add menu bindings to new functions in image-dired.el

* lisp/image-dired.el (image-dired--with-marked): New macro for
cycling over marked thumbnails.
(image-dired-tag-thumbnail, image-dired-tag-thumbnail-remove): Can
handle now also all marked thumbnails.
(image-dired-tag-marked-thumbnails): Remove it, because it's
obsoleted by `image-dired-tag-thumbnail' now.
(image-dired-delete-marked): Use new macro
`image-dired--with-marked', and add command to menu (bug#50000).