[Feature] Email collect message hooks (#331)

- Add email collect hook on creating conversation
- Merge contact if it already exist

spec/factories/conversations.rb

@@ -16,6 +16,7 @@ FactoryBot.define do
         channel: create(:channel_widget, account: conversation.account)
       )
       conversation.contact ||= create(:contact, account: conversation.account)
+      conversation.contact_inbox ||= create(:contact_inbox, contact: conversation.contact, inbox: conversation.inbox)
     end
   end
 end