test(admin): cover access key info CLI dispatch

[overtrue]

Summary

• Add a focused CLI integration test for rc admin access-key info --json
• Assert alias-based dispatch reaches /rustfs/admin/v3/info-access-key and preserves the returned access-key metadata in JSON output

Evidence

Recent origin/main added admin access-key info in #227. Existing coverage checked parser/help and the S3 admin client endpoint, but did not cover the CLI command wiring through alias resolution and JSON output.

Validation

• cargo test -p rustfs-cli --test admin_access_key
• cargo fmt --all --check
• git diff --check
• make pre-commit