feat(dev-infra): standard CLI commands using yargs (#36326)

Creates a standard model for CLI commands provided by ng-dev.
Allows for us to have any of the tools/scripts extend to be
included in the ng-dev command, or be standalone using the same
yargs parser.

PR Close #36326

dev-infra/commit-message/validate-file.ts

@@ -0,0 +1,21 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+import {readFileSync} from 'fs';
+import {join} from 'path';
+
+import {getRepoBaseDir} from '../utils/config';
+
+import {validateCommitMessage} from './validate';
+
+/** Validate commit message at the provided file path. */
+export function validateFile(filePath: string) {
+  const commitMessage = readFileSync(join(getRepoBaseDir(), filePath), 'utf8');
+  if (validateCommitMessage(commitMessage)) {
+    console.info('√  Valid commit message');
+  }
+}