Work items: Add edit button to Parent widget

What does this MR do and why?

1. Add edit button to parent widget, disable inline editing
2. When not in edit mode, add a h3 above the value as a landmark in the sidebar. In edit mode, visually hide it and put in label/field
3. Rename existing parent widget to work_item_parent_inline.vue

Issue - #429143 (closed)

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Before	After
	https://www.loom.com/share/e0c4116931f64b5d826ba7fa2156c836?sid=b78a7acc-56d1-41d3-9de9-14766b85a9e8

How to set up and validate locally

1. In rails console enable flags

   Feature.enable(:work_items_mvc)
   Feature.enable(:work_items_mvc_2)

2. Visit any task/objective/keyresult work item, i.e. http://127.0.0.1:3000/flightjs/Flight/-/work_items/43. If you don't have any you can go to issue list page of a project and create a task or OKR`

3. Edit the parent

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 #429143 (closed)