Function places::storage::bookmarks::public_node::fetch_public_tree_with_depth

pub fn fetch_public_tree_with_depth(
    db: &PlacesDb, 
    item_guid: &SyncGuid, 
    target_depth: &FetchDepth
) -> Result<Option<PublicNode>>

Call fetch_tree with a depth parameter and convert the result to a ProtoBookmark, and ensure the requested item's position and parent info are provided as well.