common/logging: Move Log::Entry declaration to a separate header

This reduces the load of requiring to include std::chrono in all files which include log.h

src/core/hle/kernel/k_auto_object_container.cpp

@@ -2,6 +2,8 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include <algorithm>
+
 #include "core/hle/kernel/k_auto_object_container.h"
 
 namespace Kernel {

src/core/hle/service/lbl/lbl.cpp

@@ -2,6 +2,7 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include <cmath>
 #include <memory>
 
 #include "common/logging/log.h"