STYLE: Remove new, do make_unique_for_overwrite in NeighborhoodAllocator

Replaced `new` with `make_unique_for_overwrite` in its copy-constructor. Removed
`new` and `delete[]` from its documentation, as suggested by Mihail Isakov.

Following C++ Core Guidelines, September 23, 2022, "Avoid calling `new` and `delete`
explicitly", from http://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Rr-newdelete

Author: N-Dekker

Modules/Core/Common/include/itkNeighborhoodAllocator.h

@@ -60,15 +60,15 @@ class NeighborhoodAllocator
   /** Defaulted destructor */
   ~NeighborhoodAllocator() = default;
 
-  /** Allocates memory using new() */
+  /** Allocates memory. */
   void
   Allocate(unsigned int n)
   {
     m_Data = make_unique_for_overwrite<TPixel[]>(n);
     m_ElementCount = n;
   }
 
-  /** Deallocates memory using delete[](). */
+  /** Deallocates memory. */
   void
   Deallocate()
   {
@@ -79,7 +79,7 @@ class NeighborhoodAllocator
   /** Copy constructor. */
   NeighborhoodAllocator(const Self & other)
     : m_ElementCount(other.m_ElementCount)
-    , m_Data(new TPixel[other.m_ElementCount])
+    , m_Data(make_unique_for_overwrite<TPixel[]>(other.m_ElementCount))
   {
     std::copy_n(other.m_Data.get(), m_ElementCount, m_Data.get());
   }