Is your feature request related to a problem? Please describe.

We are currently composing and creating a version of our own zarf init, but references for artifacts, images, and charts have to be proxied. There is a way to do this registries using --registry-override, and for the gitea image using --set AGENT_IMAGE_DOMAIN, but there are two conspicuous ones where it is not configurable:

• In packages/zarf-registry/zarf.yaml, the location of the injector binary is zarf-init-resources.s3.us-east-1.amazonaws.com; if this was a variable with a default, it would make things a little easier
• In packages/gitea/zarf.yaml, dl.gitea.io is not overrideable, at least not easily.

Describe the behavior you'd like

Both of these values should be set as variables in their respective zarf.yaml files, and set to defaults with the current values. They should thus be overrideable using a --set flag on zarf package create

Describe alternatives you've considered

I am currently using a sed command to do this instead:

        sed -i-bk 's|zarf-init-resources\.s3\.us-east-1\.amazonaws.com|our-proxied-path.com|' packages/zarf-registry/zarf.yaml
        sed -i-bk 's|dl\.gitea\.io|our-proxied-path.com|' packages/gitea/zarf.yaml
        zarf package create . --confirm ...