Resolve "Update dependency to Material-UI 5.0"

I would suggest waiting with the merge until the portal is migrated as well, so we can test the changes more thoroughly by installing it locally in the portal using verdaccio. But we definitely have to merge this one and release it before we can merge the portal migration.

Still, it can already be reviewed, so issues can be solved early.

Note: This MR contains 4 commits with breaking changes!

Closes #17 (closed)