feat: add Grok authentication plugin with OAuth support

- Introduced a new Grok authentication plugin, including essential files such as main.ts, provider.ts, and resources.ts.
- Implemented OAuth2 device authorization flow in oauth.ts, allowing users to sign in with xAI.
- Added model discovery and quota management functionalities in models.ts and resources.ts.
- Created a JSON configuration file (plugin.json) for plugin metadata and permissions.
- Included SVG asset for the Grok icon.
- Developed comprehensive tests in grok_test.ts to ensure functionality and reliability of the plugin.

server/plugins/build-in/grok-auth/main.ts

@@ -0,0 +1,16 @@
+import { defineProviderPlugin } from "cursor-byok:plugin";
+import { grokDeviceOAuth } from "./oauth.ts";
+import { grokProvider } from "./provider.ts";
+import { credentialImport, presentAccount, refreshAccount, RESOURCE_TYPE } from "./resources.ts";
+
+export default defineProviderPlugin({
+  providers: [grokProvider],
+  resources: [{
+    type: RESOURCE_TYPE,
+    displayName: { "en-US": "Grok accounts", "zh-CN": "Grok 账号" },
+    add: [grokDeviceOAuth],
+    import: credentialImport,
+    present: presentAccount,
+    refresh: refreshAccount,
+  }],
+});