[Tests] Button

[nowyDEV]

https://github.com/nordcloud/GNUI/tree/master/src/components/button
https://master.du3gff836giqw.amplifyapp.com/?path=/docs/components-button--default-story

Tasks:

• Add tests for component listed above, example test cases:
  • Rendering of ButtonIcon based on provided initialState
  • Rendering of dynamic styles with severity medium/low
  • Working as Anchor (as="a", linkTo, href)