[P_UI] Added django settings for p_ui (#5343)

* Added django settings for pui

* Fix: server version is not loaded on initial load

* Moved server version out of server selector icon

* Use polling only for WSL

* Added comment and extracted to constant instead of function

* Default show server selector to false if not in dev mode

* Refactored hostList settings

* Move json serialization into global scope

* Show server selector in netlify builds

* Use demo server for netlify

* Renamed netilfy mode to dev or demo mode

* Translate for netlify

* Dont use translation in main as the are not working there

InvenTree/config_template.yaml

@@ -240,6 +240,15 @@ remote_login_header: HTTP_REMOTE_USER
 #   hide_admin_link: true
 #   hide_password_reset: true
 
+# Platform UI options
+# pui_settings:
+#   server_list:
+#     my_server1:
+#       host: https://demo.inventree.org/api/
+#       name: InvenTree Demo
+#   default_server: my_server1
+#   show_server_selector: false
+
 # Custom flags
 # InvenTree uses django-flags; read more in their docs at https://cfpb.github.io/django-flags/conditions/
 # Use environment variable INVENTREE_FLAGS or the settings below