feat: Builder for creating Campaign conversations (#2192)

- Builder for creating Campaign conversations
- Widget endpoint to fetch the campaigns

spec/controllers/api/v1/widget/events_controller_spec.rb

@@ -9,7 +9,7 @@ RSpec.describe '/api/v1/widget/events', type: :request do
   let(:token) { ::Widget::TokenService.new(payload: payload).generate_token }
 
   describe 'POST /api/v1/widget/events' do
-    let(:params) { { website_token: web_widget.website_token, name: 'webwidget.triggered' } }
+    let(:params) { { website_token: web_widget.website_token, name: 'webwidget.triggered', event_info: { test_id: 'test' } } }
 
     context 'with invalid website token' do
       it 'returns unauthorized' do
@@ -32,7 +32,7 @@ RSpec.describe '/api/v1/widget/events', type: :request do
         expect(response).to have_http_status(:success)
         expect(Rails.configuration.dispatcher).to have_received(:dispatch)
           .with(params[:name], anything, contact_inbox: contact_inbox,
-                                         event_info: { browser_language: nil, widget_language: nil, browser: anything })
+                                         event_info: { test_id: 'test', browser_language: nil, widget_language: nil, browser: anything })
       end
     end
   end