Create Rust logic for DCAP Quote Verification

[nick-mobilecoin]

DCAP quote verification wrapper around the FFI created in #3

Some constraints to be aware of:

• The C SGX libraries are not available on all platforms needing to verify.
• The enclaves themselves may need to verify a provided quote.

Breaking this up into multiple pieces (idea taken signal's list in dcap.rs)

• Extract the quote bytes to a Rust type #25
• Verify the quote certificate chain #28
  • Make quote verification no_std #34
• Verify no keys in the chain have been revoked.
• Verify the Quoting Enclave is from a suitable source and is up to date.
  • Verify the quoting enclave report body #18
  • Verify the status of the Intel® SGX TCB described in the chain.
• Verify the enclave measurements in the Quote reflect an enclave identity expected.
  • Verify enclave report body #21
  • Verify the attestation key #22
• Utilize RustCrypto for SecP256R1 #27