DAST Site profile selector - add support for Authentication, Request headers & Excluded Urls - Frontend

• backend counterpart: #225406 (closed)

Summary

Designs for reference

Please see the epic at &3771 (closed) for any updated design

Implementation plan

• Update ee/app/assets/javascripts/on_demand_scans/components/profile_selector/site_profile_selector.vue with
  • Authentication fields if Enable authentication is set to true:
    • Authenticated Site: the URL where the login form can be found
    • Username
    • Password
    • Username Form Field:
    • Password Form Field:
  • List the Request Headers if present
  • List the Excluded URLs if present
• Extend the GraphQL query to include the fields
• Update specs