Updates the Dockerfile with changes suggested by @GWnbsp  in #43 (comment)

### Summary of Changes
1. **ARG Statements:** Introduced `ARG` statements for Node.js and Debian versions, making the Dockerfile more customizable.
2. **SHELL Command:** Changed the default shell to Bash with certain options enabled, improving robustness.
3. **Chromium Installation:** Updated Chromium installation to use Google's signing keys and repositories, aiming for more secure and up-to-date packages.
4. **Chromium Version:** Added a step to save Chromium's version into `/etc/chromium-version` for reference.
5. **Directory Creation:** Added a new directory /app/data in the container's filesystem.
6. **CMD Change:** Changed the CMD to start Node.js server (server.js) instead of using yarn serve.
7. **General Cleanup and Comments:** Code has been refactored for better readability and detailed comments have been added for clarity.
8. **Dependency Installation:** Kept yarn install and the removal of the Yarn cache, but the command is more streamlined.
9. **Other Minor Changes:**
  - Added flags like `-qq` and `--no-install-recommends` for quieter and optimized installation.
  - Enhanced cleanup with `rm -rf /var/lib/apt/lists/*.`

# Conflicts:
#	Dockerfile

(cherry picked from commit 4e70e16)