[Enhancement]: Assign brands to generated products

[layoutd]

Describe the solution you'd like

Since Brands has been added to core, generated products should be assigned 0-N brands as well (similar to categories and tags).

Describe alternatives you've considered

Leaving the brands field blank, but since it is visible in the product list by default, having values there makes sense.

Additional context

https://github.com/woocommerce/woocommerce/pull/50165#top

[masteradhoc]

+1 would be amazing

[masteradhoc]

@layoutd check please my new PR to get this feature added into Smooth Generator :)

[layoutd]

Thanks for the PR @masteradhoc, I've been disconnected for a few months. I'll try to take a look when I'm back online next week!