Types: Update LayotPosition (#8555)

Author: kurkle

types/layout.d.ts

@@ -1,6 +1,6 @@
 import { ChartArea } from './geometric';
 
-export type LayoutPosition = 'left' | 'top' | 'right' | 'bottom' | 'chartArea';
+export type LayoutPosition = 'left' | 'top' | 'right' | 'bottom' | 'center' | 'chartArea' | {[scaleId: string]: number};
 
 export interface LayoutItem {
 	/**

types/tests/layout/position.ts

@@ -0,0 +1,11 @@
+import { LayoutPosition } from '../../index.esm';
+
+export const left: LayoutPosition = 'left';
+export const right: LayoutPosition = 'right';
+export const top: LayoutPosition = 'top';
+export const bottom: LayoutPosition = 'bottom';
+export const center: LayoutPosition = 'center';
+export const axis: LayoutPosition = { x: 10 };
+
+// @ts-expect-error invalid position
+export const invalid: LayoutPosition = 'none';