Implement Discovery PLATFORM logic in Rust

This commit introduces NativeRemoteAuthService used by ReamoteAuth as an
interface toward Rust platform and protocol implementation

Design doc: go/remote-auth-manager-fishfood-design

Test: built successfully.
Bug: : 291333048
Change-Id: If2fcfee1c637d17bbc417a26ea39dc97062e6bc3
7 files changed