Fix double login authentication (#628)

Co-authored-by: Danielle Foré <danielle@elementary.io>

data/io.elementary.greeter.policy.in

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE policyconfig PUBLIC
+ "-//freedesktop//DTD PolicyKit Policy Configuration 1.0//EN"
+ "http://www.freedesktop.org/standards/PolicyKit/1.0/policyconfig.dtd">
+<policyconfig>
+  <vendor>elementary</vendor>
+  <vendor_url>https://elementary.io/</vendor_url>
+
+  <action id="io.elementary.greeter.restart">
+    <description>Restart the Login &amp; Lock screen</description>
+    <message>Permission is needed to restart the Login &amp; Lock Screen</message>
+    <icon_name>preferences-system</icon_name>
+    <defaults>
+      <allow_any>auth_admin</allow_any>
+      <allow_inactive>auth_admin</allow_inactive>
+      <allow_active>yes</allow_active>
+    </defaults>
+    <annotate key="org.freedesktop.policykit.imply">org.freedesktop.systemd1.manage-units</annotate>
+  </action>
+
+</policyconfig>

data/meson.build

@@ -26,6 +26,14 @@ i18n.merge_file(
     install_dir: join_paths(get_option('datadir'), 'metainfo'),
 )
 
+i18n.merge_file(
+    input: 'io.elementary.greeter.policy.in',
+    output: 'io.elementary.greeter.policy',
+    po_dir: join_paths(meson.source_root (), 'po', 'extra'),
+    install_dir: join_paths(get_option('datadir'), 'polkit-1', 'actions'),
+    install: true
+)
+
 install_data(
     meson.project_name() + '.conf',
     install_dir: join_paths(get_option('sysconfdir'), 'lightdm')