[KeyManager] Add rust unit tests and Linters to presubmit CI

Currently only the `golang` subsystem unit tests are validated. We should,
1. Add the `rust` KCC subsystem unit tests as presubmit CI tests.
2. Add rust linters for checking the code format for lint errors.

Start by locating the presubmit CI configuration and the Rust KCC subsystem tests. Confirm how the existing golang subsystem tests are registered, then identify the Rust linting and formatting checks. Done means Rust unit tests and linters run successfully as presubmit CI checks.

Written by the indexing model from the issue text.