Allow moving inlinetasks using org-metaup/down

* lisp/org.el (org-metaup, org-metadown): Use
`org-drag-elementbackward'/`org-drag-element-forward' to move
inlinetasks.

lisp/org.el

@@ -17090,7 +17090,7 @@ for more information."
    ((org-at-table-p) (org-call-with-arg 'org-table-move-row 'up))
    ((and (featurep 'org-inlinetask)
          (org-inlinetask-in-task-p))
-    (user-error "Dragging inline tasks is not supported"))
+    (org-drag-element-backward))
    ((org-at-heading-p) (call-interactively 'org-move-subtree-up))
    ((org-at-item-p) (call-interactively 'org-move-item-up))
    (t (org-drag-element-backward))))
@@ -17123,7 +17123,7 @@ commands for more information."
    ((org-at-table-p) (call-interactively 'org-table-move-row))
    ((and (featurep 'org-inlinetask)
          (org-inlinetask-in-task-p))
-    (user-error "Dragging inline tasks is not supported"))
+    (org-drag-element-forward))
    ((org-at-heading-p) (call-interactively 'org-move-subtree-down))
    ((org-at-item-p) (call-interactively 'org-move-item-down))
    (t (org-drag-element-forward))))