Add github actions to pull requests.

[arne-z]

Add a github action running build, lint, and test jobs that runs automatically on pull requests.

[ruegenbfr]

Would it be beneficial to use one job instead ? So the setup would run only once, like e.g.:

     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
           node-version: 18
       - id: ci
          run: npm ci
       - run: npm run build:qa
       - if:  ${{ (success() || failure()) && steps.id.outcome=='success' }}
         run: npm run test
       - if:  ${{ (success() || failure()) && steps.id.outcome=='success' }}
         run: npm run lint

[arne-z]

Is this cleared to merge now @ruegenbfr?