SVSM draft specification (v1.01 draft #3)

Attached is the next version of the draft SVSM specification with the
following changes since the previous version:

  - APIC emulation protocol added
    - Coconut-SVSM will need to be audited, as the current APIC emulation
      code does not completely match the "Alternate Injection Support"
      specification on which this protocol is based.
  - Reboot protocol added
  - Core protocol v2 update:
    - New flag to allow fallback from 2M to 4K during SVSM_CORE_PVALIDATE
      when RMPADJUST/PVALIDATE return size mismatch

Please review. If there are no or only minor comments, this draft will
become the next version of the specification.

Thanks,
Tom