Update attestation for a key

[areed]

Currently a new key has to be created every time a new certificate is authorized with the acme device attestation protocol. This allows a new attestation to be generated with fresh qualifying data from the CA.

Name of feature:

Pain or issue this feature alleviates:

Why is this important to the project (if not answered above):

Is there documentation on how to use this feature? If so, where?

In what environments or workflows is this feature supported?

Linux

In what environments or workflows is this feature explicitly NOT supported (if any)?

Windows

Supporting links/other PRs/issues:

💔Thank you!

[hslatman]

The test error is likely caused by not using the ctx and opening the TPM using the existing logic. There's a bit of plumbing to ensure the right command channel is set in all cases, incl. the in-process simulator for testing. See https://github.com/smallstep/crypto/blob/8684dc8bf25a0502f4c01cba205218c3cb09495a/tpm/key.go#L212C2-L215C30 for an example.

It's nice to see the new tpm2 API being used, but I'm not sure if it's compatible with the existing plumbing as described above. If it is: great; otherwise would advise to use the legacy package.