Convert StomachBehavior to a component/system + rejig body namespaces (#5249)

* Convert StomachBehavior to a component/system + rejig body namespaces

* test

* slightly more namespace changes

* remove

* Hello?????

* fuck you github test runner

* reviews

* oobsy!

Content.Server/Body/Components/StomachComponent.cs

@@ -0,0 +1,69 @@
+using System.Collections.Generic;
+using Content.Server.Body.Systems;
+using Content.Shared.Body.Components;
+using Content.Shared.FixedPoint;
+using Robust.Shared.Analyzers;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Serialization.Manager.Attributes;
+using Robust.Shared.ViewVariables;
+
+namespace Content.Server.Body.Components
+{
+    [RegisterComponent, Friend(typeof(StomachSystem))]
+    public class StomachComponent : Component
+    {
+        public override string Name => "Stomach";
+
+        public float AccumulatedFrameTime;
+
+        /// <summary>
+        ///     How fast should this component update, in seconds?
+        /// </summary>
+        [DataField("updateInterval")]
+        public float UpdateInterval = 1.0f;
+
+        /// <summary>
+        ///     What solution should this stomach push reagents into, on the body?
+        /// </summary>
+        [DataField("bodySolutionName")]
+        public string BodySolutionName = SharedBloodstreamComponent.DefaultSolutionName;
+
+        /// <summary>
+        ///     Initial internal solution storage volume
+        /// </summary>
+        [DataField("maxVolume")]
+        public FixedPoint2 InitialMaxVolume { get; private set; } = FixedPoint2.New(100);
+
+        /// <summary>
+        ///     Time in seconds between reagents being ingested and them being
+        ///     transferred to <see cref="SharedBloodstreamComponent"/>
+        /// </summary>
+        [DataField("digestionDelay")]
+        public float DigestionDelay = 20;
+
+        /// <summary>
+        ///     Used to track how long each reagent has been in the stomach
+        /// </summary>
+        [ViewVariables]
+        public readonly List<ReagentDelta> ReagentDeltas = new();
+
+        /// <summary>
+        ///     Used to track quantity changes when ingesting & digesting reagents
+        /// </summary>
+        public class ReagentDelta
+        {
+            public readonly string ReagentId;
+            public readonly FixedPoint2 Quantity;
+            public float Lifetime { get; private set; }
+
+            public ReagentDelta(string reagentId, FixedPoint2 quantity)
+            {
+                ReagentId = reagentId;
+                Quantity = quantity;
+                Lifetime = 0.0f;
+            }
+
+            public void Increment(float delta) => Lifetime += delta;
+        }
+    }
+}