refactor(dev): 移动头文件位置

include/frontend/SyntaxTreePrinter.h

@@ -0,0 +1,9 @@
+#pragma once
+
+#include <iosfwd>
+
+#include "antlr4-runtime.h"
+
+// 以树状缩进形式直接打印 ANTLR parse tree。
+void PrintSyntaxTree(antlr4::tree::ParseTree* tree, antlr4::Parser* parser,
+                     std::ostream& os);