Updates required for QAT

See MR in core.

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

+/********************************************************************************
+ * Copyright (c) 2023 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_ABSIMPL_H_
+#define AIDGE_CPU_OPERATOR_ABSIMPL_H_
+
+#include "aidge/backend/OperatorImpl.hpp"
+#include "aidge/operator/Abs.hpp"
+#include "aidge/utils/Registrar.hpp"
+#include "aidge/utils/Types.h"
+#include <memory>
+#include <vector>
+
+namespace Aidge {
+// class Abs_Op;
+
+// compute kernel registry for forward and backward
+class AbsImplForward_cpu
+    : public Registrable<AbsImplForward_cpu, std::tuple<DataType, DataType>, void(const std::size_t, const void*, void*)> {
+};
+class AbsImplBackward_cpu
+    : public Registrable<AbsImplBackward_cpu, std::tuple<DataType, DataType>, void(const std::size_t, const void*, void*)> {
+};
+
+class AbsImpl_cpu : public OperatorImpl {
+public:
+    AbsImpl_cpu(const Abs_Op& op) : OperatorImpl(op, "cpu") {}
+
+    static std::unique_ptr<AbsImpl_cpu> create(const Abs_Op& op) {
+        return std::make_unique<AbsImpl_cpu>(op);
+    }
+
+    Elts_t getNbRequiredProtected(const IOIndex_t inputIdx) const override final;
+    void forward() override;
+};
+
+namespace {
+static Registrar<Abs_Op> registrarAbsImpl_cpu("cpu", Aidge::AbsImpl_cpu::create);
+}
+}  // namespace Aidge
+
+#endif /* AIDGE_CPU_OPERATOR_ABSIMPL_H_ */