Device Linking and better linking ui (#13645)

Co-authored-by: AJCM-git <60196617+AJCM-git@users.noreply.github.com>
Co-authored-by: Visne <39844191+Visne@users.noreply.github.com>
Co-authored-by: ElectroJr <leonsfriedrich@gmail.com>
Co-authored-by: metalgearsloth <comedian_vs_clown@hotmail.com>

Content.Server/DeviceLinking/Systems/AutoLinkSystem.cs

@@ -0,0 +1,37 @@
+using Content.Server.DeviceLinking.Components;
+using Content.Server.MachineLinking.System;
+
+namespace Content.Server.DeviceLinking.Systems;
+
+/// <summary>
+/// This handles automatically linking autolinked entities at round-start.
+/// </summary>
+public sealed class AutoLinkSystem : EntitySystem
+{
+    [Dependency] private readonly DeviceLinkSystem _deviceLinkSystem = default!;
+
+    /// <inheritdoc/>
+    public override void Initialize()
+    {
+        SubscribeLocalEvent<AutoLinkTransmitterComponent, MapInitEvent>(OnAutoLinkMapInit);
+    }
+
+    private void OnAutoLinkMapInit(EntityUid uid, AutoLinkTransmitterComponent component, MapInitEvent args)
+    {
+        var xform = Transform(uid);
+
+        foreach (var receiver in EntityQuery<AutoLinkReceiverComponent>())
+        {
+            if (receiver.AutoLinkChannel != component.AutoLinkChannel)
+                continue; // Not ours.
+
+            var rxXform = Transform(receiver.Owner);
+
+            if (rxXform.GridUid != xform.GridUid)
+                continue;
+
+            _deviceLinkSystem.LinkDefaults(null, uid, receiver.Owner);
+        }
+    }
+}
+