Add support for tracking Enhanced Commerce

[erikdemarco]

Please add support to track woocommerce event via enhanced commerce.

Currently the plugin only adds 'ecommerce:"dataLayer"' which will not track anything. You should put transaction data to the datalayer for yandex to start tracking.

Example of tracking event via enhanced ecommerce:
=> https://yandex.com/support/metrica/data/e-commerce.html#e-commerce__ex-product-add