refactor: use export global variables instead of express

src/common.ts

@@ -14,6 +14,7 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 import {SCConfigFile} from '@openstapps/core';
+import {Validator} from '@openstapps/core-tools/lib/validate';
 import {Logger} from '@openstapps/logger';
 import * as config from 'config';
 import {BackendTransport} from './notification/BackendTransport';
@@ -23,3 +24,7 @@ export const mailer = BackendTransport.getTransportInstance();
 export const logger = new Logger(mailer);
 
 export const configFile: SCConfigFile = config.util.toObject();
+
+export const validator = new Validator();
+
+export const isTestEnvironment = process.env.NODE_ENV !== 'production';