fix(api): resolve type unsafety of redundant params in KEX protocol inits

[rmlibre]

Description

The __init__ of key exchange protocol classes called by X25519 accept a key_exchange_type key-word argument &, for all except the 2DH client class, a my_identity_key argument. However, the latter is always an instance of the former. This is an API mistake, as accepting both is redundant & facilitates inconsistencies / type unsafety.

Links to relevant files:

• aiootp/_typing/_keygens.py
• aiootp/keygens/curve_25519/double_diffie_hellman_client.py
• aiootp/keygens/curve_25519/double_diffie_hellman_server.py
• aiootp/keygens/curve_25519/triple_diffie_hellman_client.py
• aiootp/keygens/curve_25519/triple_diffie_hellman_server.py
• aiootp/keygens/curve_25519/x25519.py

Expected behavior

The DoubleDiffieHellmanClient, DoubleDiffieHellmanServer, TripleDiffieHellmanClient, & TripleDiffieHellmanServer classes should be instantiable after accepting the argument of either key_exchange_type, or an instance of that type as my_identity_key, but not both. Types should be checked with protocols from the Typing class.

[rmlibre]

Resolved by (714754d)

Changes to Protocol classes in aiootp/_typing/_keygens.py were necessary to allow type-checking during runtime.

Tests for the changes were added to tests/test_X25519_Ed25519.py