Log structured channel id

Since most log messages no longer include the channel ID in their text,
this commit updates the test logger to output the structured channel ID
instead. The ID is truncated for readability.

Author: joostjager

lightning/src/util/test_utils.rs

@@ -1700,7 +1700,9 @@ impl Logger for TestLogger {
 	fn log(&self, record: Record) {
 		let context =
 			format!("{} {} [{}:{}]", self.id, record.level, record.module_path, record.line);
-		let s = format!("{:<55} {}", context, record.args);
+		let chan_id = record.channel_id.map(|id| format!("{}", id));
+		let chan_str = chan_id.as_deref().and_then(|s| s.get(..6)).unwrap_or("");
+		let s = format!("{:<55} {:<6} {}", context, chan_str, record.args);
 		#[cfg(ldk_bench)]
 		{
 			// When benchmarking, we don't actually want to print logs, but we do want to format