downloads: split file and containers (#13581)

Splits the definitions into two dicts, while joining then for now to
preserve the downloads dict.

Update all consumers of the variables, which are roughly:
- manual includes of the download role (which will be removed in the
  short future)
- install tasks using the resolved 'dest' to find the artefacts

This will make further division of the downloads role easier.

roles/download/tasks/main.yml

@@ -16,17 +16,26 @@
     - download
     - upload
 
-- name: Download | Download files / images
-  include_tasks: "{{ include_file }}"
+- name: Download | Download files
+  include_tasks: download_file.yml
   loop: "{{ [] if skip_downloads
+               else
+            (downloads_file.values() | selectattr('enabled'))
+          }}"
+  vars:
+    download: "{{ download_defaults | combine(item) }}"
+  when:
+    - (download_run_once and inventory_hostname == download_delegate) or (group_names | intersect(download.groups) != [])
+
+- name: Download | Download images
+  include_tasks: download_container.yml
+  loop: "{{ [] if (skip_downloads or not download_container)
             else (
-              (downloads | combine(kubeadm_images)).values()
+              (downloads_container | combine(kubeadm_images)).values()
               | selectattr('enabled')
             )
           }}"
   vars:
     download: "{{ download_defaults | combine(item) }}"
-    include_file: "download_{% if download.container %}container{% else %}file{% endif %}.yml"
   when:
-    - (not download.container) or (download.container and download_container)
     - (download_run_once and inventory_hostname == download_delegate) or (group_names | intersect(download.groups) != [])