Access refactor

Access is now done through a list of access lists, instead of the necessary/sufficient system that was extremely confusing.

Added a "deny" list so you can screw over sec.

Cleaned the API up so it all uses sets and such.

PDA now relays access read-only to fix edge cases.

Content.Server/Interfaces/IAccess.cs

@@ -1,11 +1,34 @@
+using System;
+using Content.Server.GameObjects.Components.Access;
 using System.Collections.Generic;
 
+#nullable enable
+
 namespace Content.Server.Interfaces
 {
+    /// <summary>
+    ///     Contains access levels that can be checked to see if somebody has access with an <see cref="AccessReader"/>.
+    /// </summary>
     public interface IAccess
     {
-        public List<string> GetTags();
+        /// <summary>
+        ///     The set of access tags this thing has.
+        /// </summary>
+        /// <remarks>
+        ///     This set may be read-only. Check <see cref="IsReadOnly"/> if you want to mutate it.
+        /// </remarks>
+        ISet<string> Tags { get; }
 
-        public void SetTags(List<string> newTags);
+        /// <summary>
+        ///     Whether the <see cref="Tags"/> list is read-only.
+        /// </summary>
+        bool IsReadOnly { get; }
+
+        /// <summary>
+        ///     Replaces the set of access tags we have with the provided set.
+        /// </summary>
+        /// <param name="newTags">The new access tags</param>
+        /// <exception cref="NotSupportedException">If this access tag list is read-only.</exception>
+        void SetTags(IEnumerable<string> newTags);
     }
 }