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/report-alpha.api.md

@@ -5,6 +5,7 @@
 ```ts
 import { AnyApiRef } from '@backstage/core-plugin-api';
 import { ApiHolder } from '@backstage/core-plugin-api';
+import { ApiRef } from '@backstage/frontend-plugin-api';
 import { ComponentType } from 'react';
 import { ConfigurableExtensionDataRef } from '@backstage/frontend-plugin-api';
 import { CustomFieldValidator } from '@backstage/plugin-scaffolder-react';
@@ -198,6 +199,9 @@ export type FormFieldExtensionData<
   schema?: FieldSchema<z.output<TReturnValue>, z.output<TUiOptions>>;
 };
 
+// @alpha (undocumented)
+export const formFieldsApiRef: ApiRef<ScaffolderFormFieldsApi>;
+
 // @alpha (undocumented)
 export type FormValidation = {
   [name: string]: FieldValidation | FormValidation;
@@ -272,6 +276,12 @@ export type ScaffolderFormDecoratorContext<
   ) => void;
 };
 
+// @alpha (undocumented)
+export interface ScaffolderFormFieldsApi {
+  // (undocumented)
+  loadFormFields(): Promise<FormField[]>;
+}
+
 // @alpha (undocumented)
 export function ScaffolderPageContextMenu(
   props: ScaffolderPageContextMenuProps,

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[]>;
+}