Add seed to solidus bolt demo

[DanielePalombo]

Demo application doesn't have any product/users etc. In order to test it we should provide at least the sample data.

https://solidus-bolt-demo.herokuapp.com/products

[Naokimi]

Seeds were already setup in the code, but because of not working automation I had to run the manually which I have done today.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It might be closed if no further activity occurs. Thank you for your contributions.