graph/db: implement ForEachNodeDirectedChannel and ForEachNodeCacheable

Here we add the `ForEachNodeDirectedChannel` and `ForEachNodeCacheable`
SQLStore implementations which then lets us run
`TestGraphTraversalCacheable` and `TestGraphCacheForEachNodeChannel`
against SQL backends.

sqldb/sqlc/graph.sql.go

@@ -533,6 +533,25 @@ func (q *Queries) GetNodeFeaturesByPubKey(ctx context.Context, arg GetNodeFeatur
 	return items, nil
 }
 
+const getNodeIDByPubKey = `-- name: GetNodeIDByPubKey :one
+SELECT id
+FROM nodes
+WHERE pub_key = $1
+  AND version = $2
+`
+
+type GetNodeIDByPubKeyParams struct {
+	PubKey  []byte
+	Version int16
+}
+
+func (q *Queries) GetNodeIDByPubKey(ctx context.Context, arg GetNodeIDByPubKeyParams) (int64, error) {
+	row := q.db.QueryRowContext(ctx, getNodeIDByPubKey, arg.PubKey, arg.Version)
+	var id int64
+	err := row.Scan(&id)
+	return id, err
+}
+
 const getNodesByLastUpdateRange = `-- name: GetNodesByLastUpdateRange :many
 SELECT id, version, pub_key, alias, last_update, color, signature
 FROM nodes
@@ -879,6 +898,48 @@ func (q *Queries) ListChannelsByNodeID(ctx context.Context, arg ListChannelsByNo
 	return items, nil
 }
 
+const listNodeIDsAndPubKeys = `-- name: ListNodeIDsAndPubKeys :many
+SELECT id, pub_key
+FROM nodes
+WHERE version = $1  AND id > $2
+ORDER BY id
+LIMIT $3
+`
+
+type ListNodeIDsAndPubKeysParams struct {
+	Version int16
+	ID      int64
+	Limit   int32
+}
+
+type ListNodeIDsAndPubKeysRow struct {
+	ID     int64
+	PubKey []byte
+}
+
+func (q *Queries) ListNodeIDsAndPubKeys(ctx context.Context, arg ListNodeIDsAndPubKeysParams) ([]ListNodeIDsAndPubKeysRow, error) {
+	rows, err := q.db.QueryContext(ctx, listNodeIDsAndPubKeys, arg.Version, arg.ID, arg.Limit)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []ListNodeIDsAndPubKeysRow
+	for rows.Next() {
+		var i ListNodeIDsAndPubKeysRow
+		if err := rows.Scan(&i.ID, &i.PubKey); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
 const listNodesPaginated = `-- name: ListNodesPaginated :many
 SELECT id, version, pub_key, alias, last_update, color, signature
 FROM nodes