fs: move method definition from header

We are defining the definition of function in the header file itself. It
should be defined in the source file instead of the header file.

PR-URL: #36256
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

src/node_file.cc

@@ -2534,6 +2534,9 @@ void Initialize(Local<Object> target,
               use_promises_symbol).Check();
 }
 
+BindingData* FSReqBase::binding_data() {
+  return binding_data_.get();
+}
 }  // namespace fs
 
 }  // end namespace node

src/node_file.h

@@ -109,7 +109,7 @@ class FSReqBase : public ReqWrap<uv_fs_t> {
 
   void MemoryInfo(MemoryTracker* tracker) const override;
 
-  BindingData* binding_data() { return binding_data_.get(); }
+  BindingData* binding_data();
 
  private:
   std::unique_ptr<FSContinuationData> continuation_data_;