Move common things to AppCore from GuiApp 2

src/AppCommon/FileTime.App.Core.Abstraction/Services/IKeyInputHandler.cs

@@ -0,0 +1,8 @@
+using FileTime.App.Core.Models;
+
+namespace FileTime.App.Core.Services;
+
+public interface IKeyInputHandler
+{
+    Task HandleInputKey(Keys key, SpecialKeysStatus specialKeysStatus, Action<bool> setHandled);
+}