Fix checkbox tabbing

[niklasmh]

Checklist

• [x] I have ran yarn lint-check.
• [x] I have ran yarn chromatic such that other people can review my UI changes at chromaticqa.com.
• [ ] I have created a new component.
  • [ ] I have made sure that the component is exported from ./src/index.ts.
  • [ ] I have created stories for my component.

Notes to other people

• [ ] I have made global changes. (Global CSS or Storybook itself)
• [ ] I have added new depenencies.

About the pull request

Tabbing did not work. The current solution is based on hiding the checkbox behind the styled (fake) checkbox. It now acts an actual checkbox, maintaining focus border and check using keyboard.

Screenshots

See chromatic

[plusk]

Closing this since tabbing seems to work on several of our machines.