Implement magboots. (#2988)

Got an alert and action and everything.

Content.Shared/GameObjects/Components/SharedMagbootsComponent.cs

@@ -0,0 +1,35 @@
+using System;
+using Content.Shared.GameObjects.Components.Movement;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Serialization;
+
+namespace Content.Shared.GameObjects.Components
+{
+    public abstract class SharedMagbootsComponent : Component, IMoveSpeedModifier
+    {
+        public sealed override string Name => "Magboots";
+        public sealed override uint? NetID => ContentNetIDs.MAGBOOTS;
+
+        public abstract bool On { get; set; }
+
+
+        protected void OnChanged()
+        {
+            MovementSpeedModifierComponent.RefreshItemModifiers(Owner);
+        }
+
+        public float WalkSpeedModifier => On ? 0.85f : 1;
+        public float SprintSpeedModifier => On ? 0.65f : 1;
+
+        [Serializable, NetSerializable]
+        public sealed class MagbootsComponentState : ComponentState
+        {
+            public bool On { get; }
+
+            public MagbootsComponentState(bool @on) : base(ContentNetIDs.MAGBOOTS)
+            {
+                On = on;
+            }
+        }
+    }
+}