Remote device: context menu in left panel does not show "add as bookmark"

### Problem

there is no "add to bookmarks" in the context menu when you right click a remote device

since the entry disappears when unmounted, the first reflex is to add to bookmarks to keep a reference

"add to bookmarks" is present when right clicking an empty space in the folder, but not in the left pane

### Proposal

add a context menu entry, "add to bookmarks"

or alternatively checkmark to make the entry persistent when unmounted, so one can click to mount it again

### Prior Art (Optional)

_No response_