PlantHolderVisualizer component system refactor (#10091)

* Converted PlantHolderVisualizer to component and system.

* Cleaned up Botany folder.

* Converted initialization of HydroTrayVisualizer under PlantHolderVisualizerSystem to it's own GenericVisualizer.

* Cleaned up hydro_tray.yml.

Content.Client/Botany/Components/PlantHolderVisualsComponent.cs

@@ -0,0 +1,6 @@
+namespace Content.Client.Botany.Components;
+
+[RegisterComponent]
+public sealed class PlantHolderVisualsComponent : Component
+{
+}