chore: Add assigned_count to conversation APIs (#2665)

spec/controllers/api/v1/accounts/conversations_controller_spec.rb

@@ -29,6 +29,7 @@ RSpec.describe 'Conversations API', type: :request do
         expect(response).to have_http_status(:success)
         body = JSON.parse(response.body, symbolize_names: true)
         expect(body[:data][:meta][:all_count]).to eq(1)
+        expect(body[:data][:meta].keys).to include(:all_count, :mine_count, :assigned_count, :unassigned_count)
         expect(body[:data][:payload].first[:messages].first[:id]).to eq(message.id)
       end
 
@@ -68,7 +69,9 @@ RSpec.describe 'Conversations API', type: :request do
             as: :json
 
         expect(response).to have_http_status(:success)
-        expect(JSON.parse(response.body, symbolize_names: true)[:meta][:all_count]).to eq(1)
+        body = JSON.parse(response.body, symbolize_names: true)
+        expect(body[:meta].keys).to include(:all_count, :mine_count, :assigned_count, :unassigned_count)
+        expect(body[:meta][:all_count]).to eq(1)
       end
     end
   end