refactor(users): change system.users from list to dict keyed by username

roles/global_defaults/tasks/validation.yml

@@ -261,13 +261,16 @@
     fail_msg: "Invalid system sizing. Check system.cpus, system.memory, and system.disks[0].size."
     quiet: true
 
-- name: Validate at least one user is defined
+- name: Validate at least one user with a password is defined
+  vars:
+    _pw_users: "{{ system_cfg.users | dict2items | selectattr('value.password', 'defined') | list }}"
   ansible.builtin.assert:
     that:
-      - system_cfg.users | default([]) | length > 0
-      - system_cfg.users[0].name is defined and (system_cfg.users[0].name | string | length) > 0
-      - system_cfg.users[0].password is defined and (system_cfg.users[0].password | string | length) > 0
-    fail_msg: "At least one user with a name and password must be defined in system.users[]."
+      - system_cfg.users | default({}) | length > 0
+      - _pw_users | length > 0
+      - _pw_users[0].key | string | length > 0
+      - _pw_users[0].value.password | string | length > 0
+    fail_msg: "At least one user with a password must be defined in system.users."
     quiet: true
   no_log: true