CUDAWrapper: Move select device to dedicated wrapper

common/CUDAWrapper.cpp

@@ -0,0 +1,14 @@
+// Copyright (2019-2023) Paul Scherrer Institute
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef JFJOCH_USE_CUDA
+
+#include "CUDAWrapper.h"
+
+int32_t get_gpu_count() {
+    return 0;
+}
+
+void set_gpu_count(int32_t dev_id) {}
+
+#endif