Add source code to our images

[dervoeti]

Distribute the exact source code (including custom patches!) that was used to build the product in the final images. Also include source code for non-products components if possible (kcat, Phoenix, nifi-opa-authorizer, ...).

[lfrancke]

This is something that we should document in my opinion. I don't know where to be honest though. Somewhere in the vicinity of the SBOM docs maybe?
And I'd like to have release notes as well please.

I think this is fantastic and we should write about it.

[dervoeti]

Regarding documentation:
Yeah it's worth mentioning, but I'm also not sure where. I could add a sentence or two here:
https://docs.stackable.tech/home/stable/guides/viewing-and-verifying-sboms/
Or maybe here:
https://docs.stackable.tech/home/stable/product-information/

Created a draft PR for this.

Release note

We've added source code snapshots directly into our container images to further improve transparency and the debugging experience. Each container image now includes .tar.gz archives containing the exact source code used to build that specific version of the product. They can be found within the /stackable directory of each container image.

[dervoeti]

By the way: Should we do this for our operators as well? Would be more consistent. On the other hand: We don't apply custom patches there.