Add ConnectAsync to DefaultBrowserLogin for consistency with DeviceCodeLogin

[petrsnd]

DeviceCodeLogin provides both Connect() and ConnectAsync() with CancellationToken support, giving callers proper async/cancellation control.

DefaultBrowserLogin.Connect() currently blocks synchronously on AuthorizationCodeExtractor.Listen() and hardcodes Console.CancelKeyPress for cancellation. This means:

• No way to cancel programmatically (e.g., timeout after N seconds)
• Blocks the calling thread with no async alternative
• Inconsistent API surface across login packages

Proposed change:

• Add ConnectAsync(string appliance, ..., CancellationToken cancellationToken) to DefaultBrowserLogin
• Make AuthorizationCodeExtractor.Listen cancellation-token-aware (or add an async overload)
• Accept a caller-provided CancellationToken instead of hardcoding Console.CancelKeyPress
• Keep existing Connect() as a sync wrapper for backward compatibility