This commit adds support for the Fetch API's mode and redirect options when using HttpClient with the withFetch provider.

The change includes:

• Added mode and redirect to the HttpRequestInit interface
• Modified FetchBackend to pass the options
• Modifed in simple function in xhr to show warning messages
• Added unit tests to validate behavior

Motivation / Use Cases

The mode and redirect options are particularly useful for:

• mode controls the request's CORS policy ('cors', 'no-cors', 'same-origin'), helping manage security boundaries and cross-origin resource sharing.

• redirect determines how redirects are handled ('follow', 'manual', 'error'), allowing developers to explicitly accept, reject, or handle redirections manually.

• These options help ensure secure data access across origins, enforce strict network policies, and give developers more control over how external resources are handled.

Proposed Solution

• Add mode and redirect to the HttpRequestInit interface
• Implement property handling in the HttpRequest class
• Pass the options through FetchBackend to the native Fetch API
• Maintain full backward compatibility

Examples of New Usage

// POST request with mode and redirect
http.post('/api/register', {
      mode: 'same-origin',
      redirect : 'follow',
}).subscribe();