Fix some friend access violations by allowing others access. (#8594)

Rename Friend attribute to Access attribute.
Updates submodule to v0.21.0.0 as well.

Content.Client/Movement/Components/ClimbingComponent.cs

@@ -3,6 +3,6 @@
 namespace Content.Client.Movement.Components;
 
 [RegisterComponent]
-[Friend(typeof(ClimbSystem))]
+[Access(typeof(ClimbSystem))]
 [ComponentReference(typeof(SharedClimbingComponent))]
 public sealed class ClimbingComponent : SharedClimbingComponent { }