Heaviside implementation

Context

CPU Implementation for the Heaviside operator.

include/aidge/backend/cpu/operator/HeavisideImpl.hpp

+/********************************************************************************
+ * Copyright (c) 2025 CEA-List
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0.
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ ********************************************************************************/
+
+#ifndef AIDGE_CPU_OPERATOR_HEAVISIDEIMPL_H_
+#define AIDGE_CPU_OPERATOR_HEAVISIDEIMPL_H_
+
+#include <cstddef> // std::size_t
+
+#include "aidge/backend/cpu/operator/OperatorImpl.hpp"
+#include "aidge/operator/Heaviside.hpp"
+#include "aidge/utils/Registrar.hpp"
+#include "aidge/utils/future_std/span.hpp"
+
+namespace Aidge {
+using HeavisideImplCpu =
+    OperatorImpl_cpu<Heaviside_Op,
+                     void(std::size_t, const void *, void *, const float),
+                     void(const float, std::size_t, const void *, void *)>;
+
+// Implementation entry point registration for operator Heaviside
+REGISTRAR(Heaviside_Op, "cpu", HeavisideImplCpu::create);
+} // namespace Aidge
+
+#endif // AIDGE_CPU_OPERATOR_HEAVISIDEIMPL_H_