Upload test coverage to codecov.

[ouphi]

What this PR changes/adds

Upload IdentityHub test coverage to codecov.
Report can be seen here: https://codecov.io/gh/agera-edc/IdentityHub/tree/feature%2F250%2F250-codecov

Why it does that

To have codecov report to see the test coverage in PRs.

Linked Issue(s)

agera-edc/MinimumViableDataspace#250

Checklist

• added appropriate tests?
• performed checkstyle check locally?
• added/updated copyright headers?
• documented public classes/methods?
• added/updated relevant documentation?
• added relevant details to the changelog? (skip with label no-changelog)
• formatted title correctly? (take a look at the CONTRIBUTING and styleguide for details)

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (main@0e22ee7). Click here to learn what that means.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #25   +/-   ##
=======================================
  Coverage        ?   90.80%           
  Complexity      ?       71           
=======================================
  Files           ?       21           
  Lines           ?      359           
  Branches        ?       15           
=======================================
  Hits            ?      326           
  Misses          ?       28           
  Partials        ?        5           

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