Cleanup folder structure

- [x] Components should be in parent folder with same name, and all related files in that folder.
- [x] Use path aliases, instead of relative paths, something like this in tsconfig:
```
"baseUrl": ".",
"paths": {
"@/*": ["./*"]
}
```
- [x] Use styleguide helper components same as in konto (`Wrapper`, `Stack`)
- [x] sShowcases can be more condensed, e.g. headings can be in one frame...
- [x] Do not use `React.FC` syntax
- [x] Remove word "Type" from types, e.g. `SectionGroupPropsType` --> `SectionGroupProps`