[spmutil] enable provisioning RMA wrapping key (RSA3k)

[timothytrippel]

RMA tokens will generated by the HSM (SPM), hashed and then sent to the DUT to be written to OTP. Additionally, they will also be encrypted with an RSA public key written to the registry. The matching private key should be provisioned within the SPM's HSM. Thus, the spmutil too must be updated to:

• spmutil should be updated to generate RSA 3K keys (marked as exportable so they can be transferred between HSMs)
• the deployment script should updated to provision softhsm2 with such keys
• update the SPM docs to include instructions for use