DAST Configuration: Implement code snippet modal

Feature epic - &5981 (closed)

Implement DastSettingsForm save action.

• When clicking on the Generate code snippet button:
  • Open the code snippet modal.
• Code snippet modal:
  • Get form profile ids, and display them in .yaml (syntax highlighting in future iterations)
  • Copy code snippet only copies the code to the clipboard.
  • Primary action copies the snippet to the clipboard and redirects to gitlab_ci_yaml_edit_url.
• Error handling.
• Add specs