Parameterize basic_memory_region to support extended memory flags

src/emulator/memory_region.hpp

@@ -2,14 +2,15 @@
 #include "memory_permission.hpp"
 #include <cstddef>
 
+template<typename PermissionType = memory_permission>
 struct basic_memory_region
 {
     uint64_t start{};
     size_t length{}; // uint64_t?
-    memory_permission permissions{};
+    PermissionType permissions{};
 };
 
-struct memory_region : basic_memory_region
+struct memory_region : basic_memory_region<>
 {
     bool committed{};
 };