Revisit containers build process

[thejoeejoee]

• current solution builds sequentially webpack, django and proxy containers, which is slow
• would be nice to revisit the order and make the build parallel, at least from part of it
• current dependencies:
  • django depends on webpack with webpack-stats.json which contains data about compiled assets
  • proxy depends on webpack with compiled assets, since these are served by proxy
  • proxy depends on django with collectstatic result, since these are also served by proxy
• so the order is webpack, django, proxy
• would be nice to have it more straighforward without magics with artifacts in deploy.yaml
• maybe integration of Werf/similar tool would be the solution