Import Alert component


## Design
Like chip, the alert component is a much-used component, but does it fit the current Altinn look?
Should it be smaller? Should it be sharper? Or should it stay the same?

## Implementation
When this is decided, the component can be added into the component library with the decided styling.

Start by reviewing the attached design image and resolving whether the Alert should be smaller, sharper, or unchanged for the current Altinn look. Once the styling is decided, add the Alert component to the component library and verify that its implementation matches the agreed design.

Written by the indexing model from the issue text.