device/virtio-nsm: Support for Nitro Secure Module device

device/virtio-nsm: Support for Nitro Secure Module device

Nitro Secure Module (NSM)[1] device is used in AWS Nitro Enclaves[2]
for stripped down TPM functionality like cryptographic attestation.
The requests to and responses from NSM device are CBOR[3] encoded.

This commit adds support for NSM device in QEMU. Although related to
AWS Nitro Enclaves, the virito-nsm device is independent and can be
used in other machine types as well. The libcbor[4] library has been
used for the CBOR encoding and decoding functionalities.

[1] https://lists.oasis-open.org/archives/virtio-comment/202310/msg00387.html
[2] https://docs.aws.amazon.com/enclaves/latest/user/nitro-enclave.html
[3] http://cbor.io/
[4] https://libcbor.readthedocs.io/en/latest/

Signed-off-by: Dorjoy Chowdhury <dorjoychy111@gmail.com>
Reviewed-by: Alexander Graf <graf@amazon.com>
Link: https://lore.kernel.org/r/20241008211727.49088-3-dorjoychy111@gmail.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>