Merge pull request #15399 from backstage/blam/break-up-scaffolder

scaffolder: Introduce the `@backstage/plugin-scaffolder-react` and move re-usable components and types there

.changeset/kind-pianos-burn.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-scaffolder-react': major
+---
+
+Re-home some of the common types, components, hooks and `scaffolderApiRef` for the `@backstage/plugin-scaffolder` to this package for easy re-use across things that want to interact with the `scaffolder`.

.changeset/wild-socks-breathe.md

@@ -0,0 +1,45 @@
+---
+'@backstage/plugin-scaffolder': minor
+---
+
+- **Deprecation** - Deprecated the following exports, please import them directly from `@backstage/plugin-scaffolder-react` instead
+
+  ```
+  createScaffolderFieldExtension
+  ScaffolderFieldExtensions
+  useTemplateSecrets
+  scaffolderApiRef
+  ScaffolderApi
+  ScaffolderUseTemplateSecrets
+  TemplateParameterSchema
+  CustomFieldExtensionSchema
+  CustomFieldValidator
+  FieldExtensionOptions
+  FieldExtensionComponentProps
+  FieldExtensionComponent
+  ListActionsResponse
+  LogEvent
+  ScaffolderDryRunOptions
+  ScaffolderDryRunResponse
+  ScaffolderGetIntegrationsListOptions
+  ScaffolderGetIntegrationsListResponse
+  ScaffolderOutputlink
+  ScaffolderScaffoldOptions
+  ScaffolderScaffoldResponse
+  ScaffolderStreamLogsOptions
+  ScaffolderTask
+  ScaffolderTaskOutput
+  ScaffolderTaskStatus
+  ```
+
+- **Deprecation** - Deprecated the `rootRouteRef` export, this should now be used from `scaffolderPlugin.routes.root`
+
+- The following `/alpha` types have removed from this package and moved to the `@backstage/plugin-scaffolder-react/alpha` package
+
+  ```
+  createNextScaffolderFieldExtension
+  FormProps
+  NextCustomFieldValidator
+  NextFieldExtensionComponentProps
+  NextFieldExtensionOptions
+  ```