Remove lazy loading icon in Chip and Avatar components

• Removed lazy-loading of icons from Avatar and Chip components. Icon strings are no longer supported.
• Updated the icon and startIcon props to require a React component of type: React.FC<React.SVGProps<SVGSVGElement>>

Usage before:

<Avatar icon=\"assistance_dog\" size=\"xs\" />
<Chip label=\"Label\" startIcon=\"plus_small\" />

Usage now:

import { AssistanceDog, PlusSmall } from \"@sj-ab/component-library.ui.icons\";

<Avatar icon={AssistanceDog} size=\"xs\" />
<Chip label=\"Label\" startIcon={PlusSmall} />