Add an offset argument in the tensor copy CPP implementation

include/aidge/data/TensorImpl.hpp

@@ -37,9 +37,9 @@ class TensorImpl_cpu : public TensorImpl {
 
     std::size_t scalarSize() const override { return sizeof(T); }
 
-    void copy(const void *src, NbElts_t length) override {
+    void copy(const void *src, NbElts_t length, std::size_t offset = 0) override {
         std::copy(static_cast<const T *>(src), static_cast<const T *>(src) + length,
-                  static_cast<T *>(rawPtr()));
+                  static_cast<T *>(rawPtr())+offset);
     }
 
     void *rawPtr() override {

unit_tests/Test_TensorImpl.cpp

@@ -57,3 +57,4 @@ TEST_CASE("Tensor creation") {
     }
   }
 }
+