🪪 feat: Microsoft Graph Access Token Placeholder for MCP Servers (#10867)

* feat: MCP Graph Token env var

* Addressing copilot remarks

* Addressed Copilot review remarks

* Fixed graphtokenservice mock in MCP test suite

* fix: remove unnecessary type check and cast in resolveGraphTokensInRecord

* ci: add Graph Token integration tests in MCPManager

* refactor: update user type definitions to use Partial<IUser> in multiple functions

* test: enhance MCP tests for graph token processing and user placeholder resolution

- Added comprehensive tests to validate the interaction between preProcessGraphTokens and processMCPEnv.
- Ensured correct resolution of graph tokens and user placeholders in various configurations.
- Mocked OIDC utilities to facilitate testing of token extraction and validation.
- Verified that original options remain unchanged after processing.

* chore: import order

* chore: imports

---------

Co-authored-by: Danny Avila <danny@librechat.ai>

api/server/services/MCP.spec.js

@@ -120,6 +120,10 @@ jest.mock('./Tools/mcp', () => ({
   reinitMCPServer: jest.fn(),
 }));
 
+jest.mock('./GraphTokenService', () => ({
+  getGraphApiToken: jest.fn(),
+}));
+
 describe('tests for the new helper functions used by the MCP connection status endpoints', () => {
   let mockGetMCPManager;
   let mockGetFlowStateManager;