Sev-snp-measure

Added
- Add optional `--vars-file` (besides `--vars-size`) for SNP-SVSM mode (by [osteffenrh](https://github.com/osteffenrh)).

Modified
- Updated dependencies: cryptography to 42.0.0

Added
- Add `--mode=snp:svsm` to calculate SNP measurements when starting with SVSM
under QEMU (by [osteffenrh](https://github.com/osteffenrh)).
- Add `--dump-vmsa` to write measured VMSAs to local files for debugging (by
[osteffenrh](https://github.com/osteffenrh)).

Modified
- Fix bad id-auth signature generation (by [shuk777](https://github.com/shuk777)).
- Verify keys given to snp-create-id-block are EC P-384 keys (by [shuk777](https://github.com/shuk777)).

Modified
- Github repository moved to the [VirTEE](https://github.com/virtee) organization.

Added
- Add `--vmm-type=ec2` to calculate SNP measurements according to the EC2 VMM, which is slightly different than the way QEMU measures the initial VM state (by [agraf](https://github.com/agraf)).

Modified
- Detect OVMF that doesn't support kernel hashes and exit with error.
- Exit with error if `--initrd`/`--append` are used without `--kernel`.

Modified
- Modify SNP measured direct boot to match the order of measured pages in QEMU for the [March 2023 patches (v3)](https://lore.kernel.org/qemu-devel/20230302092347.1988853-1-dovmuriklinux.ibm.com/) for SNP measured boot. Note that this is a **BREAKING CHANGE** if you use `--kernel` (that is, the calculated measurement will be different when compared to v0.0.4).

Added
- Add `--mode=snp:ovmf-hash` and `--snp-ovmf-hash` to allow precalculating the first part of SNP launch digest and avoid carrying the full OVMF binary for every minor OVMF change (by [agraf](https://github.com/agraf)).
- Add new utility `snp-create-id-block` which allows generating an SNP ID block from a given measurement (by [shuk777](https://github.com/shuk777)).