Move Access & AccessReader to shared. (#5798)

* git mv

* Move Access Component & system.

- Name space changes
- Rename AccessReader to AccessReaderComponent
- Also need an abstract TryGetSlot function for SharedInventoryComponent

* better TryGetSlot

* Ah yes, tests exist.

Content.Shared/Access/Systems/AccessSystem.cs

@@ -0,0 +1,24 @@
+using Content.Shared.Access.Components;
+using Robust.Shared.GameObjects;
+using System.Collections.Generic;
+
+namespace Content.Shared.Access.Systems
+{
+    public class AccessSystem : EntitySystem
+    {
+        /// <summary>
+        ///     Replaces the set of access tags we have with the provided set.
+        /// </summary>
+        /// <param name="newTags">The new access tags</param>
+        public bool TrySetTags(EntityUid uid, IEnumerable<string> newTags, AccessComponent? access = null)
+        {
+            if (!Resolve(uid, ref access))
+                return false;
+
+            access.Tags.Clear();
+            access.Tags.UnionWith(newTags);
+
+            return true;
+        }
+    }
+}