Add "Area" component about atomic-layout

[kettanaito]

The Composition component assigns the area prop directly to the Box:

atomic-layout/packages/atomic-layout/src/components/Composition.tsx

Lines 23 to 27 in ba295c7

	const createAreaComponent = (areaName: string): AreaComponent => (
	props: BoxProps,
	) => {
	return <Box area={areaName} {...props} />
	}

However, that area prop is not listed as the one Box can accept in the GenericProps interface:

atomic-layout/packages/atomic-layout-core/src/const/props.ts

Line 50 in ba295c7

export interface GenericProps {

The props signature of the Box component can accept the area prop just fine due to the key signature on the `BoxProps:

atomic-layout/packages/atomic-layout-core/src/const/props.ts

Lines 349 to 353 in ba295c7

	export interface BoxProps extends GenericProps {
	[propName: string]: any
	flex?: boolean
	inline?: boolean
	}

Also, one thing to keep in mind: Areas rendered this way will not support conditional rendering based on their presence in the areas/template props. At least, with the current setup.