Change conversation during call

- Add `CallManagerProvider` to manage calls when the user navigates away from the call interface.
- Delete `NotificationManager`. Move its logic to `CallManagerProvider`.
- Rework routing
- Rework `ConversationProvider` and `useConversationQuery` to remove
  unecessary states

GitLab: #172
Change-Id: I4a786a3dd52159680e5712e598d9b831525fb63f
diff --git a/client/src/pages/CallPending.tsx b/client/src/pages/CallPending.tsx
index 54fb916..ea2017d 100644
--- a/client/src/pages/CallPending.tsx
+++ b/client/src/pages/CallPending.tsx
@@ -189,6 +189,7 @@
 
   switch (callStatus) {
     case CallStatus.Ringing:
+    case CallStatus.Default:
       title = t('incoming_call', {
         context: state?.isVideoOn ? 'video' : 'audio',
         member0: memberName,