Add service to help fetch Security CI Report

What does this MR do?

We need to fetch security ci reports to process them and then show users. Right now we do this for dependency list feature in two places: DependenciesController and API::Dependencies. Such code duplication can be considered reasonable, but right now we're working on Licenses list feature #14732 (closed) and it's reasonable to reuse some parts of the code.

The biggest problem in fetching report is to find the right pipeline and build. This MR solves this problem as a separate service.

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• Separation of EE specific content

Performance 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

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