Rename arrow -> arrowToken for unified naming

clang/include/clang/Tooling/Syntax/Nodes.h

 /// E.g. `-> int***`.
 class TrailingReturnType final : public Tree {
 public:
   TrailingReturnType() : Tree(NodeKind::TrailingReturnType) {}
   static bool classof(const Node *N) {
     return N->kind() == NodeKind::TrailingReturnType;
   }
   // TODO: add accessors for specifiers.
-  syntax::Leaf *arrow();
+  syntax::Leaf *arrowToken();
   syntax::SimpleDeclarator *declarator();
 };
 
 /// Parameter list for a function type and a trailing return type, if the
 /// function has one.
 /// E.g.:
 ///  `(int a) volatile ` in `int foo(int a) volatile;`
 ///  `(int a) &&` in `int foo(int a) &&;`

clang/lib/Tooling/Syntax/Nodes.cpp

return llvm::cast_or_null<syntax::Expression>(
       findChild(syntax::NodeRole::ArraySubscript_sizeExpression));
 }
 
 syntax::Leaf *syntax::ArraySubscript::rbracket() {
   return llvm::cast_or_null<syntax::Leaf>(
       findChild(syntax::NodeRole::CloseParen));
 }
 
-syntax::Leaf *syntax::TrailingReturnType::arrow() {
+syntax::Leaf *syntax::TrailingReturnType::arrowToken() {
   return llvm::cast_or_null<syntax::Leaf>(
       findChild(syntax::NodeRole::TrailingReturnType_arrow));
 }
 
 syntax::SimpleDeclarator *syntax::TrailingReturnType::declarator() {
   return llvm::cast_or_null<syntax::SimpleDeclarator>(
       findChild(syntax::NodeRole::TrailingReturnType_declarator));
 }