Misc Improvements and Bug Fixes

[AndrewKahr]

Changes

• Add tests for Windows images
• Consolidate testing workflows
• Fix checking out main instead of latest tag for building images
• Fix using GITHUB_ENV rather than GITHUB_OUTPUT which broke Windows image builds
• Improve error checking on Windows editor installations
• General improvements to error checking on editor/module installations
• Hide node error spam from Unity Hub by piping stderr to null. This is ok because the errors we care about end up on stdout

Checklist

• [x] Read the contribution guide and accept the code of conduct
• [x] Readme (updated or not needed)

[github-actions[bot]]

[GabLeRoux]

The following two jobs both failed with a timeout, but everything else is green.

https://github.com/game-ci/docker/actions/runs/4675713024/jobs/8286515438?pr=206 https://github.com/game-ci/docker/actions/runs/4675713024/jobs/8286515018?pr=206

Are we ok with that?

[AndrewKahr]

I checked the timeouts and they are from Unity not exiting despite completing the build successfully in well under 15 minutes. This is a known issue but out of scope for this PR so it is acceptable. The images themselves are building and installing the correct modules which is the main thing that matters for the scope of this PR.