(PA-5805) Add Windows support in sshkeys_core

This commit enables Windows agents in the destroy_spec.rb so Windows
agents can be used in sshkeys spec tests and adds Windows as a supported
operating system in metadata.json.

Co-authored-by: kenyon <[email protected]>

Author: AriaXLi

metadata.json

@@ -44,6 +44,9 @@
     {
       "operatingsystem": "Rocky"
     },
+    {
+      "operatingsystem": "windows"
+    },
     {
       "operatingsystem": "AlmaLinux"
     },

spec/acceptance/tests/resource/ssh_authorized_key/destroy_spec.rb

@@ -1,8 +1,6 @@
 require 'spec_helper_acceptance'
 
 RSpec.context 'ssh_authorized_key: Destroy' do
-  confine :except, platform: ['windows']
-
   let(:auth_keys) { '~/.ssh/authorized_keys' }
   let(:name) { "pl#{rand(999_999).to_i}" }
   let(:custom_key_directory) { "/etc/ssh_authorized_keys_#{name}" }