support missing drive letters in PS path type (#29884)

* fixes #26623
* Test-Path (and thus `-type path` in Get-AnsibleParam) fail on a nonexistent drive letter, since it can't be mapped to a PSProvider.
* added support and basic smoke tests for

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

@@ -0,0 +1,9 @@
+#powershell
+
+#Requires -Module Ansible.ModuleUtils.Legacy
+
+$params = Parse-Args $args
+
+$path = Get-AnsibleParam -Obj $params -Name path -Type path
+
+Exit-Json @{ path=$path }