Adds unread message bubbles for widget (#943)

Co-authored-by: Sojan <sojan@pepalo.com>
Co-authored-by: Pranav Raj S <pranav@thoughtwoot.com>

spec/factories/conversations.rb

@@ -4,7 +4,6 @@ FactoryBot.define do
   factory :conversation do
     status { 'open' }
     display_id { rand(10_000_000) }
-    user_last_seen_at { Time.current }
     agent_last_seen_at { Time.current }
     locked { false }
     identifier { SecureRandom.hex }