feat(bindings/nodejs): Make PresignedRequest serializable

[suyanhanx]

As the properties of PresignedRequest are all in getter or function form, they cannot be serialized on the JS side.

Change PresignedRequest to type object to be serializable.

[Xuanwo]

they cannot be serialized on the JS side.

Does 'serialize' mean that users want to serialized the returning request directly?

This PR provides a helper function for processing.

No, it's not the job of bindings. We need to offer native-alike functions for the language.

[suyanhanx]

Does 'serialize' mean that users want to serialized the returning request directly?

Yes.

We need to offer native-alike functions for the language.

Getters or methods as part of a class cannot be serialized.
I don't think providing such a method would compromise the native-alike experience.

[Xuanwo]

Getters or methods as part of a class cannot be serialized.

If we intend to enable users to serialize the struct that we have returned, it implies a commitment on our part not to alter the layout of the struct. Therefore, returning an Object is the only viable option. Introducing a new API such as toJSON will not address this issue.

[Xuanwo]

Please update the PR's title too😜, mostly LGTM!

[Xuanwo]

Thanks a lot!