[Merged by Bors] - Add Test result tracking to codecov

[fasmat]

Motivation

The changes in this PR allow us to better keep track of flaky tests in our CI.

Description

I modified the coverage job to use gotestsum to create both a coverage report in cover.out and a junit report in junit.xml, which is then uploaded to codecov to track tests.

Test Plan

manual: code coverage workflow succeeds and data is uploaded to codecov

TODO

• [x] Explain motivation or link existing issue(s)
• [x] Test changes and document test plan
• [x] Update documentation as needed
• [x] Update changelog as needed

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 79.9%. Comparing base (86ac1f4) to head (7525500). Report is 4 commits behind head on develop.

:white_check_mark: All tests successful. No failed tests found.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #6472 +/- ## ======================================= Coverage 79.9% 79.9% ======================================= Files 353 353 Lines 46432 46435 +3 ======================================= + Hits 37122 37142 +20 + Misses 7210 7198 -12 + Partials 2100 2095 -5 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[fasmat]

The report can be found here: https://app.codecov.io/gh/spacemeshos/go-spacemesh/tests/add-test-tracking-codecov

[fasmat]

bors merge

[spacemesh-bors[bot]]

Pull request successfully merged into develop.

Build succeeded:

• ci-status
• systest-status