fix: reflect gcds-button disabled prop to support :host([disabled]) styles (#894)

Author: melaniebmn

packages/web/src/components/gcds-button/gcds-button.tsx

@@ -88,7 +88,7 @@ export class GcdsButton {
   /**
    * The disabled attribute for a <button> element.
    */
-  @Prop() disabled: boolean;
+  @Prop({ reflect: true }) disabled: boolean;
 
   @Watch('disabled')
   validateDisabled(newValue: boolean) {