Add token-id to dastSiteTokenCreateMutation

The id is needed when creating a site validation mutation.

Note: The component that is consuming the mutation is already
assuming the id is within the response data.

ee/app/assets/javascripts/dast_site_profiles_form/graphql/dast_site_token_create.mutation.graphql

 mutation dastSiteTokenCreate($projectFullPath: ID!, $targetUrl: String!) {
   dastSiteTokenCreate(input: { projectFullPath: $projectFullPath, targetUrl: $targetUrl }) {
+    id
     token
     errors
   }