Make the unit test results and code coverage more visible

[lanthoor]

I have checked the following:

• [X] I've searched existing issues and found nothing related to my issue.

Describe the feature you want to add

Currently, the unit test results are not published to the pull requests, and coverage is not even measured. This allows merging of PRs that breaks the unit tests. The ask is to implement enforcement of these.

Proposal

1. Add a matrix based job for unit tests and make all of them "Required" check.
2. Add test result reporting.
3. Add coverage measurement.
4. Add coverage reporting.

Mockups or Images of the feature

Something like this for coverage