feat: Re-export x25519_dalek

[lu-zero]

This way downstream crates not have to explicitly import the
x25519_dalek crate and sync it up when needed.

[Noah-Kennedy]

I'm not really a fan of the whole pattern of re-exporting stuff from other crates unless there is a good reason to do so, like preventing naming collisions.

[lu-zero]

You are using those types as key part of your API, users cannot opt out and they have to ensure that they keep the two crates in sync in their Cargo.toml. It is far from pleasant over time.

[nappa85]

I've the same problem with other crates, first of all opentelemetry-otlp using an old tonic version and not re-exporting it.
If you're exposing another crate types, it's a best practice to re-export the crate to avoid people to chase the version you're using, for you it's a simple pub use, for us it's a lot less stress

[lu-zero]

Are there any chances to consider this patch? I can rebase it if that's the case.

[Noah-Kennedy]

I think I'm fine with this. If you resolve the conflicts, I'll sign off.