cli assemble support

Summary:
Call our wrapper to assemble an Android build of helloworld.

Changelog: [Internal]

Differential Revision: D58287785

packages/helloworld/cli.flow.js

@@ -19,7 +19,7 @@ import {
   launchApp,
   launchSimulator,
 } from './lib/ios';
-import {app, apple} from '@react-native/core-cli-utils';
+import {android, app, apple} from '@react-native/core-cli-utils';
 import {Option, program} from 'commander';
 import {readFileSync} from 'fs';
 import {Listr} from 'listr2';
@@ -110,6 +110,16 @@ const getBuildSettings = (mode: 'Debug' | 'Release'): BuildSettings => {
 
 const build = program.command('build');
 
+build.command('android').action(async () => {
+  const {build, assemble} = android({
+    name: 'app',
+    cwd: cwd.android,
+    mode: 'Debug',
+    sdk: process.env.ANDROID_HOME ?? env.ANDROID_SDK ?? '',
+  });
+  await run(assemble());
+});
+
 build
   .command('ios')
   .description('Builds your app for iOS')