feat: allow for custom registry

This patch adds a simple CLI which can mirror all the images needed
as well as allow for simple override for `atmosphere_image_repository`
for all images.
diff --git a/release-please-config.json b/release-please-config.json
index 1629f46..38ec1d5 100644
--- a/release-please-config.json
+++ b/release-please-config.json
@@ -4,7 +4,7 @@
       "release-type": "python",
       "draft": true,
       "extra-files": [
-        "roles/atmosphere/defaults/main.yml",
+        "atmosphere/operator/constants.py",
         "galaxy.yml"
       ]
     }