Gets the selected product option choices of a product on the Product Page.
This function is currently only available for Wix Studio sites.
The getQuantity() function returns a Promise that is resolved when the selected product option choices are retrieved. Product option choices are returned as key:value pairs that are created in the Products tab of the dashboard. Each key corresponds to an option name, and its values correspond to the choices for this option. For example, {color: "white", size: "m"}.