Package/rewrite `push_artifacts` as a Docker (or even JS) action in GHA
... and stop including this as a submodule for GHA builds.,

After that we can change from "clone whole kaitai_struct with all the submodules" to only "clone compiler + tests", as cloning ~20-30 of submodules which don't get used (e.g. docs, visualizer, all the runtimes) is quite wasteful (we spend 20-25 seconds alone only on checkout).

_Originally posted by @GreyCat in https://github.com/kaitai-io/kaitai_struct/pull/1044#discussion_r1271291293_
