replace deprecated "rewriter.create()" pattern

refactor PIM to Pim everywhere except for the accelerator name

src/PIM/Conversion/SpatialToPim/SpatialToPimPatterns.hpp

@@ -0,0 +1,12 @@
+#pragma once
+#include "mlir/IR/PatternMatch.h"
+
+namespace onnx_mlir {
+
+namespace spatial {
+
+// TODO: Add here eventual patterns
+
+}
+
+} // namespace onnx_mlir