feat: add summary to action output

[R-Raposo]

This change implements adding the summary to the action's output, as discussed here.

There's this PR open #607, but I think it doesn't quite work according to tests I did, with workflows using this action with the changes applied.

[abelbraaksma]

This is great and would open the door for writing test summary comments! Hope @dorny can take a look? 🙏

[jozefizso]

Hi @R-Raposo, thanks for this change.

Please, keep the PR focused to only adding the summary output variable.

[jozefizso]

Remove the changes to dotnet-trx and golang-json parsers as those are unrelated to this PR.

[jozefizso]

Plase, do changes on feature branches, as PRs submitted from the main branch are to editable by maintainers.

[R-Raposo]

hello @jozefizso, can you please check the PR again, to see if it's ok now? I've got some changes to the licences file when running npm run package, let me know if I should remove this from the PR.

[R-Raposo]

Plase, do changes on feature branches, as PRs submitted from the main branch are to editable by maintainers.

Sorry, we are already using a fork of this repo in SwissPost, so it was more convenient to just create a PR from the fork. Will keep in mind for the future.