Dont override md-classes when adding className prop to button and link

[kajsaeggum]

Describe your changes

Changed order of applied props to button and link elements. Otherwise adding a className property when using MdLink or MdButton component will effectively remove the internal classes that style them correctly.

Also made sure that the resulting classes added on the element include both the internal classes and any applied from the outside, so that it is possible to further style the component where it is being used.

NB: If allowing users of the component library to extend styling in this way is accepted, the same logic should be added to all the components, not just MdLink and MdButton as I've done here.

Checklist before requesting a review

• I have performed a self-review and test of my code
• If new component: Is story for component created in stories-folder?
• If new component: Is tsx-file import added to packages/react/index.tsx?
• If new component: Is css-file added to packages/css/index.css?

[Jaanesen]

Ser kjempefint ut, mangler også en package.json bump for å kunne legges inn i npm

[Jaanesen]

👍💃