Enhance Telegram notification system with optional link support

- Updated NotifyUserAsync method in TelegramNotifier to accept an optional linkPath parameter for dynamic URL generation.
- Modified various command handlers to utilize the new linkPath feature, providing users with relevant links in their notifications.
- Adjusted ITelegramNotifier interface documentation to reflect the changes in method signature and functionality.
- Enhanced unit tests to verify the correct invocation of the updated NotifyUserAsync method.

backend/tests/PnvPanel.Application.Tests/Admin/Users/DeleteUserCommandHandlerTests.cs

@@ -101,7 +101,7 @@ public class DeleteUserCommandHandlerTests
             );
         await _telegramNotifier
             .Received(1)
-            .NotifyUserAsync(userId, Arg.Any<string>(), Arg.Any<CancellationToken>());
+            .NotifyUserAsync(userId, Arg.Any<string>(), Arg.Any<string?>(), Arg.Any<CancellationToken>());
         await _identityService.Received(1).DeleteUserAsync(userId, Arg.Any<CancellationToken>());
 
         var audit = Assert.Single(dbContext.AuditLogs.Local);