Add GraphQL mutation for creating Dast::Profiles

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-only mutation for creating Dast::Profiles behind a feature flag.

Why?

this will help move us towards enabling customers to run scans without always having to select a DastSiteProfile and DastScannerProfile combination when running a dast on-demand scan i.e. a DastProfile promotes this grouping to a named abstraction.

Notes

• there is an issue to unify dast namespaces #299398 (closed)

Related Issue(s)

#295244 (closed)

Feature Flag

echo "Feature.enable(:dast_saved_scans)" | rails c

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

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