Draft: Allow user to edit timeline event

What does this MR do and why?

Describe in detail what your merge request does and why.

Adds the functionality to edit timeline event.

Also separates timeline_events_form.vue to the form itself timeline_events_form.vue and the wrapper the controls the form create_timeline_event.vue

Screenshots or screen recordings

These are strongly recommended to assist reviewers and reduce the time to merge your change.

How to set up and validate locally

1. Within a project on the left hand menu bar navigate to Monitor > Incidents
2. Open an incident (create one if needed)
3. Using the tab headings, select Timeline
4. Create a timeline entry if there isnt one
5. On the right hand side of the timeline event select edit from the more options symbol

Numbered steps to set up and validate the change are strongly suggested.

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.

Related to #344060 (closed)