Power stuff (#31314)

* Power stuff

- Add shared IsPowered
- Add shared ResolveApc
- Move PowerChangedEvent to shared for now
- Add SlimPoweredLight that actually functions how you'd expect a PoweredLight to function it id didn't have a bunch of bloat on it.

* big update

* boing

Content.Client/MachineLinking/UI/SignalTimerWindow.xaml.cs

@@ -3,6 +3,7 @@ using Robust.Client.AutoGenerated;
 using Robust.Client.UserInterface.XAML;
 using Robust.Shared.Timing;
 using Content.Client.TextScreen;
+using Robust.Client.UserInterface.Controls;
 
 namespace Content.Client.MachineLinking.UI;