[Feature] Email collect message hooks (#331)

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

spec/factories/channel/channel_widget.rb

@@ -6,5 +6,8 @@ FactoryBot.define do
     sequence(:website_url) { |n| "https://example-#{n}.com" }
     sequence(:widget_color, &:to_s)
     account
+    after(:create) do |channel_widget|
+      create(:inbox, channel: channel_widget, account: channel_widget.account)
+    end
   end
 end