Replace thread_rng with generic for pluggability #63
Description
Related to #62, Provide a way for consumers of the app to bring their own CSPRNG instead of rand's thread_rng.
- This could be done throught the addition of another generic, i.e:
<R: rand_core::CryptoRng>OR, - Adding rng capabilities to what ever crypto trait we provide trough the future
passkey-crypto