* AKPublic.Verify: Return an error if a provided PCR of the correct
digest was not included in the quote.
* AKPublic.VerifyAll: Implement VerifyAll method, which can cross-check
that provided PCRs were covered by quotes across PCR banks.
* PCR.QuoteVerified(): Introduce getter method to expose whether a
PCR value was covered during quote verification.
This change allows users to specify TPM1.2 support rather than remove it.
go-attestation will build without needing Trousers/TSPI support.
The flip-side of this is that TPM1.2 does not just work; TPM1.2 users need to
include the `tspi` build tag.
