Make report related code in MergeRequest, Pipeline, Build and JobArtifact more generic

Problem to solve

Code is added to GitLab source for each report which is basically identical:

has_test_reports
has_license_management_reports
with_test_reports
with_license_management_reports
compare_test_reports
compare_license_management_reports

etc.

Further details

Benefits would be making the code more DRY.

Proposal

These methods could be replaced by methods that take the report type in parameter.

What does success look like, and how can we measure that?

Methods are generic and adding a report type is faster and easier.

Links / references

refs #7788 (closed) Discussion https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/8032#note_111221969