Exposed note body first line on GraphQL

What does this MR do and why?

Related to the todo page migration to Vue: !147301

This MR exposes the note body's first line on the note GraphQL type.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

N.A.

How to set up and validate locally

N.A.