Resolve "Create a new Feature"

What does this MR do and why?

This MR creates a new /create route within the work item application and adds a basic form for creating a work item with title. Also, we've added a new Mutation type for createWorkItem mutation.

Screenshots or screen recordings

Empty input	Focused input with title	Unfocused input with title

How to set up and validate locally

1. Enable the work items feature flag

   Feature.enable(:work_items)

2. Go to the work item create page: /<group_name>/<project_name>/-/work_items/create (for me it's http://127.0.0.1:3000/flightjs/flight/-/work_items/create
3. Enter a work item title and click on Create button
4. You should be redirected to new work item page

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 #334812 (closed)