Implementing RetrieveCertSigningInfo and RetrieveAttestationIds traits

Implementing RetrieveCertSigningInfo and RetrieveAttestationIds traits
purely in Rust. For this we now depend on the protobuf crate.

Bug: 253906012, 253926844
Test: Build.py, run keymint TA unittests
Change-Id: I72fc1a5e282f3d3b0e8e8b599ecb287dfad5bbe9
7 files changed