Move formFieldsApiRef and ScaffolderFormFieldsApi to scaffolder-react

The formFieldsApiRef and ScaffolderFormFieldsApi type are now defined and
exported from @backstage/plugin-scaffolder-react/alpha, and re-exported
from @backstage/plugin-scaffolder/alpha for backwards compatibility.

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

plugins/scaffolder-react/src/next/api/index.ts

@@ -14,4 +14,12 @@
  * limitations under the License.
  */
 
-export { type FormField } from './types';
+import { createApiRef } from '@backstage/frontend-plugin-api';
+import { ScaffolderFormFieldsApi } from './types';
+
+export { type FormField, type ScaffolderFormFieldsApi } from './types';
+
+/** @alpha */
+export const formFieldsApiRef = createApiRef<ScaffolderFormFieldsApi>({
+  id: 'plugin.scaffolder.form-fields-loader',
+});

plugins/scaffolder-react/src/next/api/types.ts

@@ -18,3 +18,8 @@
 export interface FormField {
   readonly $$type: '@backstage/scaffolder/FormField';
 }
+
+/** @alpha */
+export interface ScaffolderFormFieldsApi {
+  loadFormFields(): Promise<FormField[]>;
+}