Add SubArray class

This allow to manipulate contiguous sub parts of arrays in the same way as arrays themselves

Note that for performances reasons, SubArray cannot be Array

src/utils/SubArray.hpp

@@ -57,6 +57,11 @@ class [[nodiscard]] SubArray
     Assert(begin + size <= array.size(), "SubView is not contained in the source Array");
   }
 
+  PUGS_INLINE
+  explicit SubArray(DataType* const raw_array, size_t begin, size_t size)
+    : m_sub_values{raw_array + begin}, m_size{size}
+  {}
+
   PUGS_INLINE
   SubArray() = delete;