Filter packages installation by OS and by group

Adds infrastructure to install OS packages depending not only on OS
(family, versions, etc) but on groups.
All the informations related to a particular package should reside in
the `pkgs` dictionnary, which takes inspiration from the `downloads`
dictionary structure.

roles/kubernetes/preinstall/tasks/0070-system-packages.yml

@@ -60,13 +60,27 @@
     - bootstrap-os
 
 - name: Install packages requirements
+  vars:
+    # The json_query for selecting packages name is split for readability
+    # see files/pkgs-schema.json for the structure of `pkgs`
+    # and the matching semantics
+    full_query: "[? value | ( {{ filters_os }} ) && ( {{ filters_groups }} ) ].key"
+    filters_groups: "groups | @ == null || [? contains(`{{ group_names }}`, @)]"
+    filters_os: "os == null || (os | ( {{ filters_family }} ) || ( {{ filters_distro }} ))"
+    dquote: !unsafe '"'
+    # necessary to workaround Ansible escaping
+    filters_distro: "distributions.{{ dquote }}{{ ansible_distribution  }}{{ dquote }} |
+                          @ == `{}` ||
+                          contains(not_null(major_versions, `[]`), '{{ ansible_distribution_major_version }}') ||
+                          contains(not_null(versions, `[]`), '{{ ansible_distribution_version }}') ||
+                          contains(not_null(releases, `[]`), '{{ ansible_distribution_release }}')"
+    filters_family: "families && contains(families, '{{ ansible_os_family }}')"
   package:
-    name: "{{ required_pkgs | union(common_required_pkgs) | flatten }}"
+    name: "{{ pkgs | dict2items | to_json|from_json | community.general.json_query(full_query) }}"
     state: present
   register: pkgs_task_result
   until: pkgs_task_result is succeeded
   retries: "{{ pkg_install_retries }}"
   delay: "{{ retry_stagger | random + 3 }}"
-  when: not (ansible_os_family in ["Flatcar", "Flatcar Container Linux by Kinvolk"] or is_fedora_coreos)
   tags:
     - bootstrap-os