Parse DAST reports using the common report format

What does this MR do?

DAST has recently been brought into line with other GitLab Secure products, moving towards using a "Common Report Format" as the JSON format of the report. This MR changes the parser to use the new fields. Future issues and MRs will remove the old fields from DAST, and also remove the old parsing logic.

This MR resolves issue #33913 (closed).

What is the Common Report Format?

There is an exercise underway by the Secure Group to standardize the format of the report generated by the different teams/tools (SAST, DAST, CS, etc). The hope is not only to reuse code components, but also to make it easier for third parties to get involved. The working title for this format is the "Common Report Format".

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• 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