Jest tests for RaAmplifyPagination & reducer

[mayteio]

Test coverage for;

nextTokenReducer

• an easy unit test, call it with {type: undefined}, expect null return
• call it with { type: CRUD_GET_LIST_SUCCESS, payload: {nextToken: undefined} } - expect null return
• call it with { type: CRUD_GET_LIST_SUCCESS, payload: {nextToken: "nextToken"} } expect nextToken return

UnconnectedRaAmplifyPagination

• <UnconnectedRaAmplifyPagination page={1} nextToken={null} /> - expect nothing returned
• <UnconnectedRaAmplifyPagination page={1} nextToken="nextToken" /> - expect(getByText(/next/i)).toBeInTheDocument()
• <UnconnectedRaAmplifyPagination page={2} nextToken=null /> - expect(getByText(/previous/i)).toBeInTheDocument()