feat: Remove reinterpret_casts from AG race timer script and add method and chat command to get current server uptime (#1673)

* use steady_clock race timer

* formatting and const

* improve time interface

* added uptime chat command

* fix bug and update documentation

* inrease /uptime GM level requirement

* update GM level for /uptime (again)

* made changes according to feedback

dNet/dServer.h

@@ -1,5 +1,6 @@
 #pragma once
 #include <string>
+#include <chrono>
 #include <csignal>
 #include "RakPeerInterface.h"
 #include "ReplicaManager.h"
@@ -80,6 +81,11 @@ public:
 
 	const ServerType GetServerType() const { return mServerType; }
 
+	[[nodiscard]]
+	std::chrono::steady_clock::duration GetUptime() const {
+		return std::chrono::steady_clock::now() - mStartTime;
+	}
+
 private:
 	bool Startup();
 	void Shutdown();
@@ -114,4 +120,5 @@ protected:
 	SystemAddress mMasterSystemAddress;
 	std::string mMasterIP;
 	int mMasterPort;
+	std::chrono::steady_clock::time_point mStartTime = std::chrono::steady_clock::now();
 };