Return additional site profile config from GraphQL

What does this MR do?

follows on from !55579 (merged) by returning additional DastSiteProfile config from GraphQL queries. two of the fields (requestHeaders and password) are secrets, so we return nil if the secrets don't exist or an agreed placeholder value if they do.

Why?

we want to give users more control over their dast on-demand scans by giving them more configuration options. as a result, we need to communicate their existence in the user interface, paying careful attention to values that are considered secret.

Related Issue(s)

• #277353 (closed)

GraphQL

Query

query project($fullPath: ID!) {
  project(fullPath: $fullPath) {
    dastSiteProfiles(first: 1) {
      nodes {
        requestHeaders
        auth { enabled url usernameField passwordField username password }
      }
    }
  }
}

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • I have included a changelog entry.
  • I have not included a changelog entry because featureflagdisabled (:security_dast_site_profiles_additional_fields).
• 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

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team