Added Check Token subaction.

src/check-token-action.ts

@@ -0,0 +1,24 @@
+import * as core from '@actions/core';
+import { fetchLatestRelease } from './core/downloader';
+
+async function run() {
+  try {
+    const repository = core.getInput('repository') || 'actions/checkout';
+    const token = core.getInput('token') || process.env.GITHUB_TOKEN;
+
+    if (!token) {
+      core.setFailed('No GitHub token provided as an input or found in GITHUB_TOKEN environment variable.');
+      return;
+    }
+
+    core.info(`Verifying GitHub token using repository ${repository}...`);
+    // Attempt to list latest release of the specified repository as a test
+    await fetchLatestRelease(repository, token);
+
+    core.info('Success: The provided GitHub token is valid and has sufficient permissions to access the repository.');
+  } catch (error: any) {
+    core.setFailed(`GitHub token verification failed. Reason: ${error.message}`);
+  }
+}
+
+run();