add back codecov.yml config

[mikaelarguedas]

Roll back https://github.com/ros2/sros2/pull/185 Using new codecov_yml_path argument: https://github.com/codecov/codecov-action?tab=readme-ov-file#arguments

This should fix coverage visualization on codecov.io

[codecov[bot]]

Codecov Report

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

Project coverage is 77.35%. Comparing base (07608ab) to head (8093d78). Report is 1 commits behind head on rolling.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## rolling #303 +/- ## ======================================== Coverage 77.35% 77.35% ======================================== Files 25 25 Lines 627 627 Branches 66 66 ======================================== Hits 485 485 Misses 121 121 Partials 21 21 ``` | [Flag](https://app.codecov.io/gh/ros2/sros2/pull/303/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros2) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/ros2/sros2/pull/303/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros2) | `77.35% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros2#carryforward-flags-in-the-pull-request-comment) to find out more.

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[mikaelarguedas]

@ahcorde @fujitatomoya thanks for the reviews!

The only change I made since your review was that I adjusted the path rewriting in the codecov.yml file

This seems to now work as expected, we'll be sure only once we get coverage on rolling with that change and PRs coming in.