Add external control to control graphql API

Add external control to edit graphql API

  1. Update ComplianceRequirementsControlInputType to allow sending external_url as a parameter.
  2. Update ComplianceRequirementsControls::CreateService to allow creating external controls.

ADR: gitlab-com/content-sites/handbook!10822 (merged)

Edited by Huzaifa Iftikhar