Add the option to build a declaration report and exit immediately

[nccatoni]

Motivation

When making modification to the manifest processing or making bulk edits to the manifests/decorators, it is very hard to test the outcome. This adds the option to dump the declarations and exit immediately making it possible to make assertion on the end to end activation/deactivation process without having to actually run the setup and test functions.

Changes

Workflow

1. ⚠️ Create your PR as draft ⚠️
2. Work on you PR until the CI passes
3. Mark it as ready for review
   • Test logic is modified? -> Get a review from RFC owner.
   • Framework is modified, or non obvious usage of it -> get a review from R&P team

🚀 Once your PR is reviewed and the CI green, you can merge it!

🛟 #apm-shared-testing 🛟

Reviewer checklist

• Anything but tests/ or manifests/ is modified ? I have the approval from R&P team
• A docker base image is modified?
  • the relevant build-XXX-image label is present
• A scenario is added, removed or renamed?
  • Get a review from R&P team

[github-actions]

CODEOWNERS have been resolved as:

conftest.py                                                             @DataDog/system-tests-core