Add a PKCS 11 Provider

[hug-dev]

This issue tracks the work of adding a new provider in PARSEC for PKCS 11 support. This new provider will implement the Provide trait to respond to clients requests. PKCS 11 will allow us to use a variety of HSM and other crypto backends.

The chosen implementation for this is to use the rust-pkcs11 crate that offers a wrapper around the PKCS 11 APIs. The configuration will contain information about the PKCS 11 library to load, the slot to use and the PIN needed to login (if needed).

cc @parallaxsecond/maintainers

[hug-dev]

This task is being addressed in #68
It only does RSA key pair creation and signing/verifying for now.

[hug-dev]

Closing ad #68 was merged. Will add new issues to complete the providers with remaining operations.