bin/static-delta: Add signature parameters to apply-offline

This allows to check the delta signature before applying it.

Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>

bash/ostree

@@ -1532,6 +1532,9 @@ _ostree_static_delta_apply_offline() {
     "
 
     local options_with_args="
+        --sign-type
+        --keys-file
+        --keys-dir
         --repo
     "