NFTStorefrontV2: Listing completed event does not provide information on royalties paid

[bymi15]

The ListingCompleted event lacks information on royalties paid.
The self.details.saleCuts should also include the royalty receiver's cut which should be represented in the event.
From simply emitting the salePrice we don't know what proportion of this amount was actually paid to the seller, and how much was paid out as royalty.

https://github.com/onflow/nft-storefront/blob/main/contracts/NFTStorefrontV2.cdc#L75