deps(rustls+openssl): re-export rustls and openssl dependencies ?

As mentioned in a discord discussion, a user relying on the `use-rustls` feature needs to also depend on `rustls` dependency making sure to match the dependency version, to properly use `rust-electrum-client` with `rustls`, as it relies on a `CryptoProvider` implementation.

Alongside that there's a lack of documentation regarding the proper usage of this project with `use-rustls` and `CryptoProvider` inner workings.

It can be solved by using the `use-rustls-ring` feature, however, it'd be easier if the users had access to a re-exported version of the `rustls`.

Also, does that also applies for `openssl` one ?