Turns GameTicker into an EntitySystem. (#4197)

* GameTicker turned into an EntitySystem

* Turns ClientGameTicker into an EntitySystem, turn NetMessages into events

* Change event names to be more consistent with the rest.

* YAML linter uses the dummy gameticker CVar override.

* Fix game ticker initialization order

* Dummy ticker won't spawn players.

* Fix character creation test

Content.IntegrationTests/ContentIntegrationTest.cs

@@ -5,10 +5,12 @@ using Content.Client.Parallax.Managers;
 using Content.Server.GameTicking;
 using Content.Server.IoC;
 using Content.Shared.CCVar;
+using Moq;
 using NUnit.Framework;
 using Robust.Server.Maps;
 using Robust.Shared;
 using Robust.Shared.ContentPack;
+using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Log;
 using Robust.Shared.Map;
@@ -57,7 +59,7 @@ namespace Content.IntegrationTests
 
             // Connecting to Discord is a massive waste of time.
             // Basically just makes the CI logs a mess.
-            options.CVarOverrides["discord.enabled"] = "false";
+            options.CVarOverrides[CVars.DiscordEnabled.Name] = "false";
 
             // Avoid preloading textures in tests.
             options.CVarOverrides.TryAdd(CVars.TexturePreloadingEnabled.Name, "false");
@@ -112,16 +114,9 @@ namespace Content.IntegrationTests
         protected ServerIntegrationInstance StartServerDummyTicker(ServerIntegrationOptions options = null)
         {
             options ??= new ServerIntegrationOptions();
-            options.BeforeStart += () =>
-            {
-                IoCManager.Resolve<IModLoader>().SetModuleBaseCallbacks(new ServerModuleTestingCallbacks
-                {
-                    ServerBeforeIoC = () =>
-                    {
-                        IoCManager.Register<IGameTicker, DummyGameTicker>(true);
-                    }
-                });
-            };
+
+            // Dummy game ticker.
+            options.CVarOverrides[CCVars.GameDummyTicker.Name] = "true";
 
             return StartServer(options);
         }