feat: add constant for proxy-config.json path

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

@@ -1,3 +1,4 @@
 export * from './api';
+export * from './proxy';
 export * from './system-types';
 export * from './volo';

npm/ng-packs/packages/schematics/src/constants/proxy.ts

@@ -0,0 +1 @@
+export const PROXY_CONFIG_PATH = '/proxy/proxy-config.json';