feat: Support logging to journald with tracing-journald

This stubs out on non-unix platforms.

Cargo.lock

@@ -797,6 +797,7 @@ dependencies = [
  "tokio-metrics",
  "tracing",
  "tracing-flame",
+ "tracing-journald",
  "tracing-opentelemetry",
  "tracing-subscriber",
 ]
@@ -5178,6 +5179,17 @@ dependencies = [
  "tracing-subscriber",
 ]
 
+[[package]]
+name = "tracing-journald"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fc0b4143302cf1022dac868d521e36e8b27691f72c84b3311750d5188ebba657"
+dependencies = [
+ "libc",
+ "tracing-core",
+ "tracing-subscriber",
+]
+
 [[package]]
 name = "tracing-log"
 version = "0.2.0"