[Tests] Modal

https://github.com/nordcloud/GNUI/tree/master/src/components/modal
https://master.du3gff836giqw.amplifyapp.com/?path=/docs/components-modal--basic-modal

Tasks:
- Create tests for `Modal` component, example scenarios:
  - Open/Close actions, verify modal is displayed/hidden
  - Content is properly rendered inside Modal
  - Provided actions are executed