feat: add method modifier enum to schematics

npm/ng-packs/packages/schematics/src/enums/index.ts

@@ -1,3 +1,4 @@
 export * from './binding-source-id';
 export * from './exception';
 export * from './import-keyword';
+export * from './method-modifier';

npm/ng-packs/packages/schematics/src/enums/method-modifier.ts

@@ -0,0 +1,6 @@
+export enum eMethodModifier {
+  Public = '',
+  Private = 'private ',
+  Async = 'async ',
+  PrivateAsync = 'private async ',
+}