feat(@angular-devkit/build-angular): add support for the poll option in the library builder

This commit adds support for polling when using the ng-packagr builder

Closes #27420

Author: alan-agius4

goldens/public-api/angular_devkit/build_angular/index.md

@@ -303,6 +303,7 @@ export type KarmaConfigOptions = ConfigOptions & {
 
 // @public
 export interface NgPackagrBuilderOptions {
+    poll?: number;
     project: string;
     tsConfig?: string;
     watch?: boolean;

packages/angular/cli/src/commands/build/long-description.md

@@ -1,5 +1,5 @@
 The command can be used to build a project of type "application" or "library".
-When used to build a library, a different builder is invoked, and only the `ts-config`, `configuration`, and `watch` options are applied.
+When used to build a library, a different builder is invoked, and only the `ts-config`, `configuration`, `poll` and `watch` options are applied.
 All other options apply only to building applications.
 
 The application builder uses the [esbuild](https://esbuild.github.io/) build tool, with default configuration options specified in the workspace configuration file (`angular.json`) or with a named alternative configuration.

packages/angular_devkit/build_angular/src/builders/ng-packagr/index.ts

@@ -47,6 +47,7 @@ export function execute(
 
       const ngPackagrOptions = {
         cacheEnabled,
+        poll: options.poll,
         cacheDirectory: join(cacheDirectory, 'ng-packagr'),
       };
 

packages/angular_devkit/build_angular/src/builders/ng-packagr/schema.json

@@ -16,6 +16,10 @@
       "type": "boolean",
       "description": "Run build when files change.",
       "default": false
+    },
+    "poll": {
+      "type": "number",
+      "description": "Enable and define the file watching poll time period in milliseconds."
     }
   },
   "additionalProperties": false,