added endpoint for get cancelled invoices

app/controllers/api/v1/accreditation_center/invoice_status_controller.rb

@@ -0,0 +1,32 @@
+module Api
+  module V1
+    module AccreditationCenter
+      class InvoiceStatusController < ::Api::V1::AccreditationCenter::BaseController
+        def index
+          username, password = Base64.urlsafe_decode64(basic_token).split(':')
+          @current_user ||= ApiUser.find_by(username: username, plain_text_password: password)
+
+          return render json: { errors: 'No user found' }, status: :not_found if @current_user.nil?
+
+          @invoices = @current_user.registrar.invoices.select { |i| i.cancelled_at != nil }
+
+          if @invoices
+            render json: { code: 1000, invoices: @invoices },
+                   status: :found
+          else
+            render json: { errors: 'No invoices' }, status: :not_found
+          end
+        end
+
+        private
+
+        def basic_token
+          pattern = /^Basic /
+          header  = request.headers['Authorization']
+          header = header.gsub(pattern, '') if header&.match(pattern)
+          header.strip
+        end
+      end
+    end
+  end
+end