feat: add fft_ifftn base (#184)

* feat: add `fft_ifftn` base

* fix: add trailing newline to base header

Author: voltjia

src/base/fft_ifftn.h

@@ -0,0 +1,39 @@
+#ifndef INFINI_OPS_BASE_FFT_IFFTN_H_
+#define INFINI_OPS_BASE_FFT_IFFTN_H_
+
+#include "operator.h"
+
+namespace infini::ops {
+
+class FftIfftn : public Operator<FftIfftn> {
+ public:
+  FftIfftn(const Tensor input, Tensor out)
+      : input_shape_{input.shape()},
+        input_strides_{input.strides()},
+        input_type_{input.dtype()},
+        out_shape_{out.shape()},
+        out_strides_{out.strides()},
+        out_type_{out.dtype()},
+        device_index_{out.device().index()} {}
+
+  virtual void operator()(const Tensor input, Tensor out) const = 0;
+
+ protected:
+  Tensor::Shape input_shape_;
+
+  Tensor::Strides input_strides_;
+
+  DataType input_type_;
+
+  Tensor::Shape out_shape_;
+
+  Tensor::Strides out_strides_;
+
+  DataType out_type_;
+
+  int device_index_{0};
+};
+
+}  // namespace infini::ops
+
+#endif