Add PlaceCentered bool to PlaceableSurfaceComponent (#2771)

* Added bool _placeCentered to check if an entity must be placed at mouse position or center of the PlaceableSurface (+ offset) when dropped.

* private variables formatted to camel case

* Use EqualsApprox in the setter for PositionOffset

* -Changed client-side SurfaceComponent to camelCase
-Added placeCentered and positionOffset to PlaceableSurfaceComponentState
-Getter and setters for placeCentered and positionOffset client-side

* Update Content.Client/GameObjects/Components/PlaceableSurfaceComponent.cs

Co-authored-by: Vera Aguilera Puerto <6766154+Zumorica@users.noreply.github.com>

* Add "_" to private vars name

* Made YAML properties camelCase

* Add "_" to private vars name

* Call Dirty() when IsPlaceable,PlaceCentered and PositionOffset are changed.

* Removed Dirty() from client.

Co-authored-by: Vera Aguilera Puerto <6766154+Zumorica@users.noreply.github.com>

Content.Shared/GameObjects/Components/SharedPlaceableSurfaceComponent.cs

@@ -1,5 +1,6 @@
 using System;
 using Robust.Shared.GameObjects;
+using Robust.Shared.Maths;
 using Robust.Shared.Serialization;
 
 namespace Content.Shared.GameObjects.Components
@@ -8,18 +9,23 @@ namespace Content.Shared.GameObjects.Components
     {
         public override string Name => "PlaceableSurface";
         public override uint? NetID => ContentNetIDs.PLACEABLE_SURFACE;
-
         public virtual bool IsPlaceable { get; set; }
+        public virtual bool PlaceCentered { get; set; }
+        public virtual Vector2 PositionOffset { get; set; }
     }
 
     [Serializable, NetSerializable]
     public class PlaceableSurfaceComponentState : ComponentState
     {
         public readonly bool IsPlaceable;
+        public readonly bool PlaceCentered;
+        public readonly Vector2 PositionOffset;
 
-        public PlaceableSurfaceComponentState(bool placeable) : base(ContentNetIDs.PLACEABLE_SURFACE)
+        public PlaceableSurfaceComponentState(bool placeable, bool centered, Vector2 offset) : base(ContentNetIDs.PLACEABLE_SURFACE)
         {
             IsPlaceable = placeable;
+            PlaceCentered = centered;
+            PositionOffset = offset;
         }
     }
 }