Implement leftover log rotation/archival for supervised nodes

This helps prevent a node from being killed/crashing in the middle
of writing a log, restarting, and eventually clobbering that log
file that never underwent the rotation/archival process.

The old `archive-log` and `post-terminate` scripts as used by
ZeekControl previously implemented this behavior, but the new logic is
entirely in the ASCII writer.  It uses ".shadow" log files stored
alongside the real log to help detect such scenarios and rotate them
correctly upon the next startup of the Zeek process.

src/logging/Manager.h

@@ -4,6 +4,9 @@
 
 #pragma once
 
+#include <ctime>
+#include <string_view>
+
 #include "../Val.h"
 #include "../Tag.h"
 #include "../EventHandler.h"
@@ -26,6 +29,19 @@ class RotationFinishedMessage;
  */
 class Manager : public plugin::ComponentManager<Tag, Component> {
 public:
+
+	/**
+	 * Returns a formatted string representing the given time.  This
+	 * string is used in the log file rotation process.
+	 */
+	static std::string FormatRotationTime(time_t t);
+
+	/**
+	 * Returns a formatted string representing the file rotation path.  This
+	 * string is used in the log file rotation process.
+	 */
+	static std::string FormatRotationPath(std::string_view path, time_t t);
+
 	/**
 	 * Constructor.
 	 */