add CI to build the container image with blubber

Jeltorequested to merge
add-production-ci into main

This change adds the required files to build the container image using blubber. The build process has some limitations:

  • we don't support buildpacks in production yet(?)
  • I was not able to use yarn but had to use npm instead
  • npm threw a TS6133 error

I'd prefer using the same build workflow (like buildpacks) across all plattforms, but I don't think the limitations above can be solved until Jan 15.

Bug: T408592

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