windows: fix list type in legacy module utils (#30483)

* windows: fix list type in legacy module utils

* only change the return for the list type instead of affecting it all

* additional null check when using an array

test/integration/targets/win_module_utils_legacy/library/testlist.ps1

@@ -0,0 +1,12 @@
+#powershell
+
+#Requires -Module Ansible.ModuleUtils.Legacy
+
+$params = Parse-Args $args
+$value = Get-AnsibleParam -Obj $params -Name value -Type list
+
+if ($value -isnot [array]) {
+    Fail-Json -obj @{} -message "value was not a list but was $($value.GetType().FullName)"
+}
+
+Exit-Json @{ count = $value.Count }

test/integration/targets/win_module_utils_legacy/tasks/main.yml

@@ -21,3 +21,21 @@
   - path: '{{ bogus_driveletter.stdout_lines[0] }}:\goodpath'
   - path: '{{ bogus_driveletter.stdout_lines[0] }}:\badpath*%@:\blar'
     should_fail: true
+
+- name: test list parameters
+  testlist:
+    value: '{{item.value}}'
+  register: list_tests
+  failed_when: list_tests|failed or list_tests.count != item.count
+  with_items:
+  - value: []
+    count: 0
+  - value:
+    - 1
+    - 2
+    count: 2
+  - value:
+    - 1
+    count: 1
+  - value: "1, 2"
+    count: 2