Resolve "Use apollo resolver for fetch/update new work item"

What does this MR do and why?

This MR is basically focussed on creating an approach to handle the new work item creation with apollo cache.

Why Doing this with cache

Doing this with cache will take us closer to unify the creation and updation process so that it is done as smoothly.

This is just the first iteration and basically an approach to update assignees, color and health status since they were the most straightforward widgets to do 🙂

Also , changed the way title and description are updated..

There will be follow up MR's for handle more widgets and maybe having the same code for creation and updation process.

**The use cases to be checked **

1. Global New epic button from the super sidebar
2. New epic button from the epics list/work items list
3. New objective from the project issues list
4. New epic from the super sidebar in group context when the work item detail is open

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

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

Current behavior
Screen_Recording_2024-05-10_at_1.19.29_PM

How to set up and validate locally

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

1. In rails console the FF

   Feature.enable(:namespace_level_work_items)
   Feature.enable(:okrs_mvc)

2. Visit any epics list / work items list http://127.0.0.1:3000/groups/gitlab-org/-/work_items or http://127.0.0.1:3000/groups/gitlab-org/-/epics

3. Click the New epic button and see that you are able to create a new work item with 3 more widgets Assignees, color and health risk

Works the same with New Epic button from the super sidebar.

Related to #458036 (closed)