[Add] Dropout Operator

Context

Update the cpu.hpp file and add the following new files for the dropout implementation based on the Bernoulli distribution:

• DropoutImp_forward_kernels.hpp
• DropoutImp.hpp
• DropoutImpl.cpp

Part of: aidge_core#183

Modified files

• aidge/aidge_backend_cpu/include/aidge/backend/cpu.hpp

Added files

• aidge_backend_cpu/include/aidge/backend/cpu/operator/DropoutImpl_forward_kernels.hpp
• aidge_backend_cpu/include/aidge/backend/cpu/operator/DropoutImpl.hpp
• aidge_backend_cpu/src/operator/DropoutImpl.cpp
• add: unit-test Test_DropoutImpl.cpp

include/aidge/backend/cpu/operator/DropoutImpl.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_DROPOUTIMPL_H_
+#define AIDGE_CPU_OPERATOR_DROPOUTIMPL_H_
+
+#include <cstddef> // std::size_t
+
+#include "aidge/backend/cpu/operator/OperatorImpl.hpp"
+#include "aidge/operator/Dropout.hpp"
+#include "aidge/utils/Registrar.hpp"
+
+namespace Aidge {
+
+// Operator implementation entry point for the backend
+using DropoutImpl_cpu = OperatorImpl_cpu<Dropout_Op,
+    void(float,
+        std::size_t,
+        unsigned int,
+        const void*,
+        void*)>;
+
+// Implementation entry point registration to Operator
+REGISTRAR(Dropout_Op, "cpu", Aidge::DropoutImpl_cpu::create);
+
+}  // namespace Aidge
+
+#endif /* AIDGE_CPU_OPERATOR_DROPOUTIMPL_H_ */