sip: origin: Always notify state changes when relevant to the UI

by adding functions to the public API which determine if state changes
should be shown to the user and use them (instead of duplicating similar
logic).

plugins/sip/calls-sip-origin.c

@@ -145,7 +145,9 @@ change_state (CallsSipOrigin         *self,
 
   g_assert (CALLS_SIP_ORIGIN (self));
 
-  if (self->state == new_state)
+  if (self->state == new_state &&
+      new_state != CALLS_ACCOUNT_STATE_ERROR &&
+      !calls_account_state_reason_is_for_ui (reason))
     return;
 
   old_state = self->state;