CICD: leverage docker images with deps pre-installed

[midleman]

Currently, the Positron repository relies on system package installations (e.g., apt-get and yarn install) and manual environment setups in GitHub runners to install dependencies and build the project. This ticket proposes transitioning to using pre-configured Docker images for installing dependencies and running tests. This would involve creating Docker images that contain all necessary system-level dependencies (Node.js, Playwright, Xvfb, etc.) and integrating Docker into the GitHub Actions pipeline for dependency installation, compilation, and testing.

Goals:
• Utilize Docker containers to create a consistent and reproducible environment for install deps, building, and testing
• Reduce the reliance on manual configuration in the CI pipeline.
• Improve the reliability, speed, and consistency of the CI pipeline by using pre-built images.

[petetronic]

There's lots of pros and cons here to discuss, let's chat with the team.