Key Agree Update

1. Add a parameter to the client key agree functions for the hashId.
   It's only really used for EcdhKyber1, but it keeps the functions
   parallel.
2. Add and update some top-of-function comments for the key agree
   functions.
3. Renamed the X25519 key agreement functions to Curve25519 to match the
   naming in the RFC.
4. Removed the temporary hashId local in the client EcdhKyber1
   function.