fix(cli): address emlautarom1 review comments on validator tests

- Add CancellationToken to validator::run and run_tests_with_timeout;
  use tokio::select! so Ctrl+C (SIGINT) cancels in-progress tests
- Replace ERR_TIMEOUT_INTERRUPTED string const with CliError::TimeoutInterrupted
  and CliError::Other("test case not supported") with CliError::TestCaseNotSupported;
  remove leading underscore from both variants in the error enum
- Remove RUSTSEC advisory ignores added to deny.toml; run cargo update
  instead — all seven advisories are resolved by updated transitive deps

Co-Authored-By: Bohdan Ohorodnii <35969035+varex83@users.noreply.github.com>

Author: varex83agent