drime: fix listings of large directories

next_page is not currently being returned on listings which is causing
the rclone listing code to go wrong. This was returned so is likely a
regression in Drime.

This changes the page counter to calculate using current_page and
last_page. last_page on the first page request is just current_page+1.
drime appears to be capping per_page to 200. as more pages are
requested, last_page increments by 1 until current_page = last_page

backend/drime/api/types.go

@@ -77,9 +77,9 @@ type Listing struct {
 	Data        []Item `json:"data"`
 	From        int    `json:"from"`
 	LastPage    int    `json:"last_page"`
-	NextPage    int    `json:"next_page"`
+	NextPageURL string `json:"next_page_url"`
 	PerPage     int    `json:"per_page"`
-	PrevPage    int    `json:"prev_page"`
+	PrevPageURL string `json:"prev_page_url"`
 	To          int    `json:"to"`
 	Total       int    `json:"total"`
 }

backend/drime/drime.go

@@ -565,10 +565,10 @@ OUTER:
 				break OUTER
 			}
 		}
-		if result.NextPage == 0 {
+		if result.CurrentPage == result.LastPage {
 			break
 		}
-		page = result.NextPage
+		page = result.CurrentPage + 1
 	}
 	return found, err
 }