graph/db: let ForEachNodeChannel take a context

graph/db/kv_store.go

@@ -3232,7 +3232,7 @@ func nodeTraversal(tx kvdb.RTx, nodePub []byte, db kvdb.Backend,
 // halted with the error propagated back up to the caller.
 //
 // Unknown policies are passed into the callback as nil values.
-func (c *KVStore) ForEachNodeChannel(nodePub route.Vertex,
+func (c *KVStore) ForEachNodeChannel(_ context.Context, nodePub route.Vertex,
 	cb func(*models.ChannelEdgeInfo, *models.ChannelEdgePolicy,
 		*models.ChannelEdgePolicy) error) error {