Correctly extend MdLink and MdTile with button/anchor-attributes

[aurorascharff]

Describe your changes

It was not possible to add button/achor-props like aria-attributes or classname to MdLink, MdTile and MdVerticalTile. Converted their props to types and extended correctly.

Checklist before requesting a review

• I have performed a self-review and test of my code
• I have added label to the PR (major, minor or patch)
• 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?

[github-actions]

Please set a versioning label of either major, minor, or patch to the pull request.

[aurorascharff]

@kajsaeggum Hei Kajsa, hva tenker du om denne løsningen? Mtp. at det var du som gjorde den opprinnelige utvidelsen av props.