WIP: Code coverage visualization for merge request diff

Sami Hiltunenrequested to merge
smh-code-coverage into master

Adds a cobertura report for visualizing code coverage when viewing merge request diffs.

GitLab docs: https://docs.gitlab.com/ee/user/project/merge_requests/test_coverage_visualization.html

Edited by Sami Hiltunen

Merge request reports