Kebab fork slug when name is changed

MR	Changes
!53544 (merged)	Implement fork project form
!55259 (merged)	Implement fork info in vue (and add fork project icon)
tbd	Add validation to form
👉 this MR	Add project-slug auto kebab case of project-name
tbd	make form responsive
tbd	Docs

What does this MR do?

This MR will make the project slug act similar to when creating a project -- it will auto kebab case the project slug when the project name is changed.

fork_form_kebab

Testing Case

This feature is behind a Feature Flag, to turn on:

Feature.enable(:fork_project_form)

1. Navigate to a project.
2. Click on the Fork button

• The project slug is pre-populated of that from the project

Project	Form

• When the project name is changed, the project slug will display as the kebab version of the project name

• The project slug will be set to what the user typed in

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • I have included a changelog entry.
  • I have not included a changelog entry because _____.
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Related to #15013 (closed)