Convert fork info into Vue and add illustration

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

What does this MR do?

This MR converts the rest of the fork new page into a Vue app. Also, it adds the SVG illustration.

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

• You see the SVG illustration

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• 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)