Prepare build workflow in GitHub

[MartinGroscheTT]

As the maintainer of the browser extension we want to have an effortless workflow to build the extension.

• The Increment of PLAT-26 is synced to https://github.com/tracetronic/ecu.test-diff
• A GitHub Actions workflow is created to automate the build process
• The workflow is triggered on push to main and on PRs to main
• Dependencies are installed and cached efficiently to speed up builds
• The built artifacts are stored as workflow artifacts for easy access
• The workflow is documented in the developer guide
• The build pipeline is successfully tested and verified