feat: added WaitForSeconds and WaitWhile yields

Engine.Core/Systems/Yields/WaitForSecondsYield.cs

@@ -0,0 +1,10 @@
+using System;
+
+namespace Engine.Core;
+
+public class WaitForSecondsYield(float seconds) : ICoroutineYield
+{
+    private readonly DateTime triggerTime = DateTime.UtcNow.AddSeconds(seconds);
+
+    public bool Yield() => DateTime.UtcNow < triggerTime;
+}

Engine.Core/Systems/Yields/WaitWhileYield.cs

@@ -0,0 +1,10 @@
+using System;
+
+namespace Engine.Core;
+
+public class WaitWhileYield(Func<bool> condition) : ICoroutineYield
+{
+    private readonly Func<bool> condition = condition;
+
+    public bool Yield() => condition.Invoke();
+}