When we are updating the note via the API, we don't have any way to prevent data lose. In this issue, we introduce a new optional parameter called original_body, which is used to check the note has not been updated since the client sending the api request has last seen the note. ### Steps to reproduce 1. Read the note as user A, user A thinks that `body` is `1234` 1. Read the note as user B, user B thinks that `body` is `1234` 1. User A submits a `updateNote` mutation and changes the body to `abcde` 1. User B submits an `updateNote` changes the body to `wxyz` \*\*without having a chance of knowing they are overriding data they've never seen. Related to: https://gitlab.com/gitlab-org/gitlab/-/issues/323808