for casting from the CompacthPublicKey parameter we need to add the notion of a kind on the CompactCiphertextList, where one kind will need to be cast thanks to an auxiliary keyswitching key and the other kind can just be expanded as before
to avoid weird situations/corner cases we remove the ability to encrypt a "normal" ciphertext from a CompactPublicKey (which consisted in expanding right after encryption)
Check-list:
[ ] Tests for the changes have been added (for bug fixes / features)
[ ] Docs have been added / updated (for bug fixes / features)
[ ] Relevant issues are marked as resolved/closed, related issues are linked in the description
[ ] Check for breaking changes (including serialization changes) and add them to commit message following the conventional commit specification
closes: please link all relevant issues
PR content/description
Check-list: