feat(ciapp): collect per-test coverage information

[jirikuncar]

Submit per-test coverage information in test.coverage tag.

This feature can be enabled using DD_CIVISIBILITY_CODE_COVERAGE_ENABLED=true environment variable.

NOTE: this is an internal PoC feature that should not be advertised in release notes yet.

Checklist

• [ ] Added to the correct milestone.
• [ ] Tests provided or description of manual testing performed is included in the code or PR.
• [ ] Library documentation is updated.
• [ ] Corp site documentation is updated (link to the PR).

[mergify[bot]]

@jirikuncar this pull request is now in conflict 😩

[mergify[bot]]

@jirikuncar this pull request is now in conflict 😩