cryptsetup: Add support for EC keys in PKCS#11 tokens

cryptsetup: Add support for EC keys in PKCS#11 tokens

Since EC keys doesn't support encryption directly, we use ECDH protocol.
We generate a pair of EC keys in the same EC group, then derive a shared secret using the generated private key and the public key in the token.
The derived shared secret is used as a volume key. The generated public key is stored in the LUKS2 JSON token header area. The generated private key is erased.
To unlock a volume, we derive the shared secret with the stored public key and a private key in the token.

Co-authored-by: MkfsSion <mkfssion@mkfssion.com>