feat: support private scoped registry on ubuntu

[nvandessel]

Changes

• Moves the creation of the .upmconfig.toml previously used for package testing, to outside the scope of package testing to support projects which contain private scoped registries. The caveats remain the same for packages, that right now it is only supported on Linux runners, and only a single private registry is supported.

Related Issues

• Closes https://github.com/game-ci/unity-test-runner/issues/271

Related PRs

• Docs PR: https://github.com/game-ci/documentation/pull/470

Successful Workflow Run Link

PRs don't have access to secrets so you will need to provide a link to a successful run of the workflows from your own repo.

• I have a successful run on a private repo, my fork fails the existing tests due to missing Unity License. If needed I could alter the main.yml to only run a single test on a Professional license to show it pass, or we could discuss any other options like sharing screenshots of action passing from private repo.

Checklist

• [x] Read the contribution guide and accept the code of conduct
• [x] Docs (If new inputs or outputs have been added or changes to behavior that should be documented. Please make a PR in the documentation repo)
• [x] Readme (updated or not needed)
• [x] Tests (added, updated or not needed)

[github-actions[bot]]

[nvandessel]

@GabLeRoux curious to get our input on this and the related issue I created/attached. Thanks! 🙏

[nvandessel]

Apologies for my coworkers reviews, I shared the PR with them among some others and they reviewed thinking it was going into our fork 😅

[webbertakken]

Released as part of https://github.com/game-ci/unity-test-runner/releases/tag/v4.3.0

[nvandessel]

Damn, that was fast. You guys rock 🤘