sogo: Allow adding IMAP accounts and changing full name

Configuration provided by David (https://discuss.freedombox.org/u/david/)

Tests:

- Install SOGo without patch and apply the patch. The app setup is run and new
version of configuration file is installed. After logging into SOGo:

  - Mail settings shows an option to add IMAP account.

  - Editing Full Name in the identity of the default account is now possible.

Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

plinth/modules/sogo/__init__.py

@@ -38,7 +38,7 @@ class SOGoApp(app_module.App):
 
     app_id = 'sogo'
 
-    _version = 2
+    _version = 3
 
     def __init__(self) -> None:
         """Create components for the app."""

plinth/modules/sogo/privileged.py

@@ -51,6 +51,10 @@ def _create_config(db_password: str):
   SOGoCalendarDefaultRoles = ("PublicViewer", "ConfidentialDAndTViewer");
   SOGoAppointmentSendEMailNotifications = YES;
   SOGoRefreshViewCheck = "every_minute";
+  /* Allow users to add their own additional IMAP accounts */
+  SOGoMailAuxiliaryUserAccountsEnabled = YES;
+  /* Allow users to change their full name in default account */
+  SOGoMailCustomFromEnabled = YES;
 
   /* Authentication */
   SOGoMaximumFailedLoginCount = "10";