Timeline event form

What does this MR do and why?

Adds UI to add and delete timeline events

Screenshots or screen recordings

add_delete_timeline_events

How to set up and validate locally

1. Enable incident_timeline feature flag.

2. Check the page for any incident issue.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.