More datahandler stuff, removed SzOperationResult.cs and made a new SzResult.cs and changed Evaluator and DataHander to utilize it

SzCore/SzResult.cs

@@ -0,0 +1,14 @@
+namespace SzCore;
+
+public class SzResult<T>
+{
+    public bool IsSuccess { get; }
+    public T? Value { get; }
+    public string? Error { get; }
+
+    protected SzResult(T? value, bool success, string? error) 
+        => (Value, IsSuccess, Error) = (value, success, error);
+
+    public static SzResult<T> Success(T value) => new(value, true, null);
+    public static SzResult<T> Failure(string error) => new(default, false, error);
+}