simulator: Write dependency logs to separate files (#7433)

This PR relates to:
- https://github.com/sigp/lighthouse/pull/7199
- -> workspace_filter has been enabled (dependency logging has been disabled)
- https://github.com/sigp/lighthouse/pull/7394
- -> file logging has been optionally enabled

Building on these, this PR enables dependency logging for the simulators. The logs are written to separate files.

The libp2p/discv5 logs:
- are saved to the directory  specified with `--log-dir`
- respects the `RUST_LOG` environment variable for log level configuration

testing/simulator/Cargo.toml

@@ -20,5 +20,6 @@ rayon = { workspace = true }
 sensitive_url  = { path = "../../common/sensitive_url" }
 serde_json = { workspace = true }
 tokio = { workspace = true }
+tracing = { workspace = true }
 tracing-subscriber = { workspace = true }
 types = { workspace = true }