Consider to use external for unused internally functions instead of public

Description

There is few functions that marked as public but, never used it interanlly. Such as:

1. BidBeasts::mint()

2. BidBeasts::burn()

3. BidBeastsNFTMarket::getListing()

4. BidBeastsNFTMarket::getHighestBid()

5. BidBeastsNFTMarket::getOwner()

Recommended Mitigation

Consider to marked those function as a external instead marked as a public, because:

• External: parameters are read directly from calldata without copying to memory

• Public: The compiler automatically creates a wrapper that copies the arguments from calldata to memory, so that the function can be called both internally and externally.