oci2disk: add the ability to pass the compression algorithm via the C…

[thees]

…OMPRESSED environment variable so that the image tag does not need to have the compression extension as a "file extension". still keep the backward compatibility with COMPRESSED=true so that the imageUrl (i.e. the image tag) is parsed for the compression algorithm

Description

Change affects the action oci2disk:

Currently the compression type needs to be in the image tag as a suffix which is a design flaw in my opinion.
This PR gives the user the ability to pass the compression type of the image by using the existing COMPRESSED env variable.

Backward compatibility is kept with COMPRESSED=true. If true, the code tries to detect the compression type the old way (the suffix of the image url, which is in most cases the "suffix" of the image tag)

Documentation is clearer now as well.

Fixes: #

How Has This Been Tested?

new unit tests for this small change, so that the given variable is respected correctly

How are existing users impacted? What migration steps/scripts do we need?

Backward compatibility is kept. Users can additionally pass the compression by using the existing COMPRESSED variable.

Checklist:

I have:

• updated the documentation and/or roadmap (if required)
• added unit or e2e tests
• provided instructions on how to upgrade

[thees]

Hi @jacobweinstock , I don't know about the process, but take a look at this PR which removes the requirement to have images tagged with the file extension at the end.
Happy to hearing from you,
Sebastian