feat(accordion-group): add the shape property and styles for the ionic theme (#29971)

- Adds support for the `shape` property in accordion group.
- Adds styles for the `"soft"`, `"round"` and `"rectangular"` shapes in the `ionic` theme
- Defaults the shape to `"round"` for the ionic theme
- Adds an e2e test for `shape` with screenshots of all shapes
- Renames the `accordion.e2e.ts` files in other tests to `accordion-group.e2e.ts` which also renames the screenshot folder

packages/angular/src/directives/proxies.ts

@@ -30,14 +30,14 @@ export declare interface IonAccordion extends Components.IonAccordion {}
 
 
 @ProxyCmp({
-  inputs: ['animated', 'disabled', 'expand', 'mode', 'multiple', 'readonly', 'theme', 'value']
+  inputs: ['animated', 'disabled', 'expand', 'mode', 'multiple', 'readonly', 'shape', 'theme', 'value']
 })
 @Component({
   selector: 'ion-accordion-group',
   changeDetection: ChangeDetectionStrategy.OnPush,
   template: '<ng-content></ng-content>',
   // eslint-disable-next-line @angular-eslint/no-inputs-metadata-property
-  inputs: ['animated', 'disabled', 'expand', 'mode', 'multiple', 'readonly', 'theme', 'value'],
+  inputs: ['animated', 'disabled', 'expand', 'mode', 'multiple', 'readonly', 'shape', 'theme', 'value'],
 })
 export class IonAccordionGroup {
   protected el: HTMLElement;