Assign Website at the time of Creation to the Default Stock

[maghamed]

Website creation. We should assign Default stock to the newly created website.

We need to pluginize website resource model

namespace Magento\Store\Model\ResourceModel;

/**
 * Website Resource Model
 *
 * @api
 * @since 100.0.2
 */
class Website extends \Magento\Framework\Model\ResourceModel\Db\AbstractDb

with afterSave plugin.
And for all newly created website (which does not have linkage to any Stock) we need to make an assignment to the Default Stock using APIs provided in PR #150