Check the short channel id between ldk and cln before passing down the value to ldk

[vincenzopalazzo]

          A short channel id can be `000x00x00` or a sequence of bytes. See the definition of the short channel id on the spec https://github.com/lightning/bolts/blob/master/07-routing-gossip.md#definition-of-short_channel_id

Originally posted by @vincenzopalazzo in #29 (comment)