Add dastSiteValidationRevoke GraphQL mutation

What does this MR do?

adds ee-specific mutation for revoking dast_site_validations.

follows on from !51678 (merged)

Why?

users need the ability to revoke permission to run an active (destructive) dast on-demand scan. this service will be used in a GraphQL mutation to facilitate this.

Related Issue(s)

• #280763 (closed)
• #276228 (closed)
• &4872 (closed)

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry behind feature flag
• [-] 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