Add a test that puts all components on an entity and checks for no exceptions (#1815)

* Add test that puts all components on an entity and checks for no exceptions

Also fix all the exceptions that happened because of this

* Add comments to the test

* Fix nullable errors

* Fix more nullable errors

* More nullable error fixes

* Unignore basic actor component

* Fix more nullable errors

* NULLABLE ERROR

* Add string interpolation

* Merge if checks

* Remove redundant pragma warning disable 649

* Address reviews

* Remove null wrappers around TryGetComponent

* Merge conflict fixes

* APC battery component error fix

* Fix power test

* Fix atmos mapgrid usages

Content.Server/GameObjects/Components/Atmos/GasMixtureHolderComponent.cs

@@ -0,0 +1,26 @@
+using Content.Server.Atmos;
+using Robust.Shared.GameObjects;
+using Robust.Shared.Serialization;
+using Robust.Shared.ViewVariables;
+
+namespace Content.Server.GameObjects.Components.Atmos
+{
+    [RegisterComponent]
+    public class GasMixtureHolderComponent : Component
+    {
+        public override string Name => "GasMixtureHolder";
+
+        [ViewVariables] public GasMixture GasMixture { get; set; } = new GasMixture();
+
+        public override void ExposeData(ObjectSerializer serializer)
+        {
+            base.ExposeData(serializer);
+
+            serializer.DataReadWriteFunction(
+                "volume",
+                0f,
+                vol => GasMixture.Volume = vol,
+                () => GasMixture.Volume);
+        }
+    }
+}