Deny List Mechanics and Authority

initialize_deny_list(collection_cap): Sets up a deny list for a collection.

add_to_deny_list(...) / remove_from_deny_list(...): Manage addresses on the deny list.

revoke_deny_list_authority(...): Revokes the ability to modify the deny list.

is_denied(...) / can_receive_art20(...): Check if an address is allowed to receive NFTs.