Implement lifecycle of a document

[hackerwins]

What would you like to be added:

Implement the lifecycle of a document.

Currently, when the user attaches the document, it is automatically created if it is not in Yorkie. And there is no way to delete the document.

We need to consider separating document creation and update and adding document deletion.

Why is this needed:

Creating, updating, and deleting resources is a common use case.

[hackerwins]

continue with #273.