Refactor standing to be ECS (#4142)

* Refactor standing to be ECS

E C S B A B Y

* DONE

* FIX IT FIX IT FIX IT

* IsDown event

* Change to methods

* Fixes

* Address some reviews

* Last of the Mohicans

* Final fixes

* Fix tests

Content.Shared/NetIDs/ContentNetIDs.cs

@@ -100,6 +100,7 @@ namespace Content.Shared.NetIDs
         public const uint LIGHT_REPLACER = 1090;
         public const uint SINGULARITY_DISTORTION = 1091;
         public const uint GRAVITY = 1092;
+        public const uint STANDING_STATE = 1093;
 
         // Net IDs for integration tests.
         public const uint PREDICTION_TEST = 10001;