core/reporter: Add missing includes and forward declarations

Adds missing inclusions to prevent potential compilation issues.

src/core/reporter.h

@@ -4,7 +4,9 @@
 
 #pragma once
 
+#include <array>
 #include <optional>
+#include <string>
 #include <vector>
 #include "common/common_types.h"
 
@@ -16,6 +18,8 @@ class HLERequestContext;
 
 namespace Core {
 
+class System;
+
 class Reporter {
 public:
     explicit Reporter(System& system);