Add OAuth support for upstream MCP servers (#381)

Co-authored-by: samanhappy <samanhappy@gmail.com>

tests/services/openApiGeneratorService.test.ts

@@ -1,3 +1,17 @@
+// Mock openid-client before importing services
+jest.mock('openid-client', () => ({
+  discovery: jest.fn(),
+  dynamicClientRegistration: jest.fn(),
+  ClientSecretPost: jest.fn(() => jest.fn()),
+  ClientSecretBasic: jest.fn(() => jest.fn()),
+  None: jest.fn(() => jest.fn()),
+  calculatePKCECodeChallenge: jest.fn(),
+  randomPKCECodeVerifier: jest.fn(),
+  buildAuthorizationUrl: jest.fn(),
+  authorizationCodeGrant: jest.fn(),
+  refreshTokenGrant: jest.fn(),
+}));
+
 import { generateOpenAPISpec, getToolStats } from '../../src/services/openApiGeneratorService';
 
 describe('OpenAPI Generator Service', () => {