message: Remove unecessary headers in HandshakeLayer.cpp
  Summary:
  Trivial cleanup.
  Pull Request resolved:
diff: #include <quic/handshake/HandshakeLayer.h>
  -#include <fizz/crypto/KeyDerivation.h>
  -#include <fizz/crypto/Sha256.h>
  -#include <fizz/protocol/Factory.h>
  -
  namespace quic {
  EncryptionLevel protectionTypeToEncryptionLevel(ProtectionType type) {
  