Integrate signing server with AWS HSM

[morri-son]

What would you like to be added:
It should be possible to use the signing server together with AWS' HSM. Since currently the HSM SDK does not allow a client to create hashes and just sign the hash, so in any case the content, here the normalized content of a component descriptor, has to be sent to the HSM.

Why is this needed:
It should be possible to sign component versions using a signing server that is integrated with HSM.