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/roles/flux/tasks/main.yml b/roles/flux/tasks/main.yml
index bb89eff..adf55a9 100644
--- a/roles/flux/tasks/main.yml
+++ b/roles/flux/tasks/main.yml
@@ -7,4 +7,4 @@
 - name: Install Flux to cluster
   run_once: true
   changed_when: false
-  ansible.builtin.command: flux install
+  ansible.builtin.command: flux install {% if atmosphere_image_repository %}--registry={{ atmosphere_image_repository }}{% endif %}