v0.3.18 release

[bradhe]

• Cleaned up telemetry package for downstream consumers
• Bump version to v0.3.18

[Copilot]

Pull Request Overview

This PR prepares the v0.3.18 release by cleaning up the telemetry package for downstream consumers and bumping the version number. Key changes include refactoring logging macros and functions, introducing enums for log configuration (LogLevel, LogDestination, and LogFormat), and updating the module reexports in lib.rs.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
crates/tower-telemetry/src/logging.rs	Refactored logging macros and added logging configuration functions.
crates/tower-telemetry/src/lib.rs	Simplified module reexports by removing duplicated logging definitions.

Comments suppressed due to low confidence (3)

crates/tower-telemetry/src/logging.rs:14

• Ensure that the change to include a namespaced key ('tower.runid') in the logged event is intentional and consistent with downstream consumers' expectations.

$crate::tracing::event!($level, "tower.runid" = %runid, "{}", format!($fmt, $($arg)+))

crates/tower-telemetry/src/logging.rs:212

• [nitpick] Consider improving the error handling by providing additional context or a fallback mechanism instead of using a simple expect message.

tracing::subscriber::set_global_default(subscriber)

crates/tower-telemetry/src/logging.rs:203

• [nitpick] Add a comment explaining the rationale for hard-coded logging directives (e.g., 'h2=off', 'tower::buffer=off', 'hyper_util=off') to assist future maintainers.

let filter = EnvFilter::new(level)\n    .add_directive("h2=off".parse().unwrap())\n    .add_directive("tower::buffer=off".parse().unwrap())\n    .add_directive("hyper_util=off".parse().unwrap());