[Keylime] Remove requirement for atomic quotes and improve validation architecture

[nate-double-u]

Keylime enables users to monitor remote nodes (file integrity and measured boot) using a hardware based cryptographic root of trust. Keylime currently uses "Atomic Quotes" of PCRs from TPM security modules which can cause some extra churn in attestation and extra work for the TPM itself. These atomic quotes are not strictly necessary and removing them would help performance and scalability of the verification and also less work on the target agents.

Mentor(s): Thore Sommer (@THS-on), Michael Peters (@mpeters)

https://github.com/cncf/mentoring/blob/main/summerofcode/2022.md#remove-requirement-for-atomic-quotes-and-improve-validation-architecture