graph/db+sqldb: implement HasChannelEdge and ChannelID

And run `TestEdgeInfoUpdates` against our SQL backends.

sqldb/sqlc/queries/graph.sql

@@ -206,6 +206,10 @@ SELECT
 FROM channel_extra_types cet
 WHERE cet.channel_id = $1;
 
+-- name: GetSCIDByOutpoint :one
+SELECT scid from channels
+WHERE outpoint = $1 AND version = $2;
+
 -- name: GetChannelsByPolicyLastUpdateRange :many
 SELECT
     sqlc.embed(c),