[RFC] Added NGINX Buildsystem github action test.

[thresheek]

Proposed changes

This adds a CI pipeline to test if the usual way of building nginx and modules work. This functionality is now not covered in the CI tests, and may be further expanded if/when #27 is merged.

I've chosen Alpine as it has most of dependencies already built, which will drastically lower the time needed for checks to succeed or fail. Also, this adds a test on the submitted PR.

Currently this fails due to #16 and it will fail later on the actual test step - the perl tests seem to have protoc paths hardcoded to whatever is used by cmake-based build system.

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING document
• If applicable, I have added tests that prove my fix is effective or that my feature works
• If applicable, I have checked that any relevant tests pass after adding my changes
• I have updated any relevant documentation (README.md and CHANGELOG.md)