Add Dependency Scanning support to Scan Execution Policies

Why are we doing this work

We want users to be able to require Dependency Scanning to run as part of a GitLab Scan Execution Security Policy.

Similar to the existing SAST scan action, the Dependency Scanning scan action will execute the Jobs/Dependency-Scanning template in a child pipeline.

Relevant links

• &7669 (closed)

Non-functional requirements

• Documentation: Scan execution policies is updated to reflect newly introduced scan: dependency_scanning action
  • doc/user/application_security/policies/scan-execution-policies.md
• Feature flag:
• Performance:
• Testing:

Implementation plan

• backend Refer to the dependency-scanning-security-policy-support branch for a PoC. The implementation will differ slightly once !100173 (merged) is merged.

Verification steps