Add DastProfileType GraphQL and specs

Background

a Dast::Profile is a description of how to run an on-demand dast scan. it is compromised of a name and description and is associated with both a DastSiteProfile and a DastScannerProfile.

What does this MR do?

adds new ee GraphQL type for representing Dast::Profiles.

Why?

development work on Dast::Profiles (nee dast saved scans) requires several mutations to be implemented (#295244 (closed), #295249 (closed)), all of which have the same return type, making it a coordination point. implementing it in a small, easy to review, merge request should help enable more effective async development.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry developer-facing change
• 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