Added structured NodeType and list_of_files table

CREATE EXTENSION IF NOT EXISTS ltree;

CREATE TYPE NodeType AS ENUM ('container', 'data', 'link');

CREATE TYPE NodeType AS ENUM ('container', 'data', 'link', 'structured');

CREATE TYPE LocationType AS ENUM ('virtual', 'tape', 'user', 'LBT');

CREATE TABLE node (

-- Stores the content of StructuredDataNodes representing a list of files.

CREATE TABLE list_of_files (

    list_node_id     BIGSERIAL NOT NULL,

    node_id          BIGSERIAL NOT NULL,

    PRIMARY KEY (list_node_id, node_id),

    FOREIGN KEY (list_node_id) REFERENCES node (node_id),

    FOREIGN KEY (node_id) REFERENCES node (node_id)

);