Create a CoCo vTPM spec draft directory

[deeglaze]

As part of the kickoff of the January 15th, 2025 special session meeting, I hope to get folks discussing requirements, constraints, and design ideas here in the form of issues and PRs. This will need at least the pandoc draft set up for contribution.

Task: create a copy of cfenner's template repo in coco/persistence

[deeglaze]

The fTPM handling for storage is related and will likely need to be afforded by the specification. The "dark period" in the paper seems analogous to my idea of switching to ephemeral mode while certain commitments are finished, if not a bit more drastic in the lost access.
https://github.com/microsoft/MSRSec/blob/master/TAs/optee_ta/fTPM/README.md