UI: Button to set emulator time based on system time in settings, under the time settings.

Partially resolves #355. I think that wanted automatic. If automatic functionality is still desired even with this change then that will be considered.

src/Ryujinx/UI/Views/Settings/SettingsSystemView.axaml.cs

@@ -1,5 +1,7 @@
 using Avalonia.Controls;
+using Avalonia.Interactivity;
 using Ryujinx.Ava.UI.ViewModels;
+using System;
 using TimeZone = Ryujinx.Ava.UI.Models.TimeZone;
 
 namespace Ryujinx.Ava.UI.Views.Settings
@@ -33,5 +35,7 @@ namespace Ryujinx.Ava.UI.Views.Settings
                 ViewModel.ValidateAndSetTimeZone(timeZone.Location);
             }
         }
+
+        private void MatchSystemTime_OnClick(object sender, RoutedEventArgs e) => ViewModel.MatchSystemTime();
     }
 }