JWT auth support

This was added to support front-end projects with a bundler. But of course, table autogen will not work

const orm = new Hasura({
  graphqlUrl: process.env.GQL_ENDPOINT,
  jwt: process.env.JWT_TOKEN,
});

orm.createTable({name: '_om_test'})
  .createField({name: 'id', isPrimary: true})
  .createField({name: 'text'})
  .createField({name: 'increment'})
  .createField({name: 'type'})
  .generateBaseFragments();