Consider adding support for OTP keys

[simo5]

PKCS#11 specify a CKO_OTP_KEY type as well as mechanisms like CKM_HOTP and CKM_HOTP_KEY_GEN which are simple enough to implement and can be useful to test facilities like notifications (CKN_OTP_CHANGED)

[harrison314]

Hello @simo5, can we provide an example of using OTP keys via CKM HOTP?