Add new webchat base_path for HMPO

Trello: https://trello.com/c/VmJdgRXL

Add this page as a base_path:
https://www.gov.uk/government/organisations/hm-passport-office/contact/webchat

With the same values for open_url, availability_url and open_url_redirect as the existing page.

Author: leenagupte

lib/webchat.yaml

@@ -2,3 +2,7 @@
   open_url: https://hmpowebchat.klick2contact.com/v03/launcherV3.php?p=HMPO&d=717&ch=CH&psk=chat_a1&iid=STC&srbp=0&fcl=0&r=Chat&s=https://hmpowebchat.klick2contact.com/v03&u=&wo=&uh=&pid=2&iif=0
   availability_url: https://hmpowebchat.klick2contact.com/v03/providers/HMPO/api/availability.php
   open_url_redirect: false
+- base_path: /government/organisations/hm-passport-office/contact/webchat
+  open_url: https://hmpowebchat.klick2contact.com/v03/launcherV3.php?p=HMPO&d=717&ch=CH&psk=chat_a1&iid=STC&srbp=0&fcl=0&r=Chat&s=https://hmpowebchat.klick2contact.com/v03&u=&wo=&uh=&pid=2&iif=0
+  availability_url: https://hmpowebchat.klick2contact.com/v03/providers/HMPO/api/availability.php
+  open_url_redirect: false