Updating CDDL schemas to match the finalized spec.

This primarily updates CDDL to allow for OEMs who wish to use P256
instead of Ed25519 to do so. One structural change of note that affects
all implementors is that SignedMacAad now includes the tag from the
COSE_Mac0 of MacedKeysToSign to prevent a potential vulnerability that
would exist if an attacker compromised the server's EEK private key.

Bug: 189018262
Test: Purely a comment change
Change-Id: I043a19c6aba0f771315d45c04ab5263b610b5de8
Merged-In: I043a19c6aba0f771315d45c04ab5263b610b5de8