Voting (#3185)

* Basic voting

* Rewrite lobby in XAML.
Working lobby voting.

* Escape menu is now XAML.

* Vote menu works, custom votes, gamemode votes.

* Vote timeouts & administration.

Basically done now.

* I will now pretend I was never planning to code voting hotkeys.

* Make vote call UI a bit... funny.

* Fix exception on round restart.

* Fix some vote command definitions.

Content.Shared/Utility/RemList.cs

@@ -0,0 +1,76 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+
+#nullable enable
+
+namespace Content.Shared.Utility
+{
+    // It's a Remie Queue now.
+
+    /// <summary>
+    ///     Simple helper struct for "iterate collection and have a queue of things to remove when you're done",
+    ///     to avoid concurrent iteration/modification.
+    /// </summary>
+    public struct RemQueue<T>
+    {
+        public List<T>? List;
+
+        public void Add(T t)
+        {
+            List ??= new();
+            List.Add(t);
+        }
+
+        public Enumerator GetEnumerator()
+        {
+            return new(List);
+        }
+
+        public struct Enumerator : IEnumerator<T>
+        {
+            private readonly bool _filled;
+            private List<T>.Enumerator _enumerator;
+
+            public Enumerator(List<T>? list)
+            {
+                if (list == null)
+                {
+                    _filled = false;
+                    _enumerator = default;
+                }
+                else
+                {
+                    _filled = true;
+                    _enumerator = list.GetEnumerator();
+                }
+            }
+
+            public bool MoveNext()
+            {
+                if (!_filled)
+                {
+                    return false;
+                }
+
+                return _enumerator.MoveNext();
+            }
+
+            void IEnumerator.Reset()
+            {
+                if (_filled)
+                {
+                    ((IEnumerator) _enumerator).Reset();
+                }
+            }
+
+            public T Current => _enumerator.Current;
+
+            object? IEnumerator.Current => Current;
+
+            void IDisposable.Dispose()
+            {
+            }
+        }
+    }
+}