Fix occasional crash after adding a contact

Sometimes, the coroutine adding the contact to the database wouldn't
have finished before we navigated to the chat for the new contact,
leading to a crash. Now we wait until that coroutine is done before
navigating.

This crash could easily be reproduced by adding a delay(1000) to
`ContactManager::add`.

Author: robinlinden

atox/src/main/kotlin/ui/addcontact/AddContactViewModel.kt

@@ -11,6 +11,7 @@ import java.util.Date
 import javax.inject.Inject
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.runBlocking
 import ltd.evilcorp.atox.tox.ToxStarter
 import ltd.evilcorp.core.repository.MessageRepository
 import ltd.evilcorp.core.vo.Contact
@@ -48,8 +49,8 @@ class AddContactViewModel @Inject constructor(
         )
     }
 
-    fun addContact(toxId: ToxID, message: String) {
-        contactManager.add(toxId, message)
+    fun addContact(toxId: ToxID, message: String) = runBlocking {
+        contactManager.add(toxId, message).join()
         addToChatLog(toxId.toPublicKey().string(), message)
     }
 }