Split Core modules into separate files

PluralKit.Core/Modules/ConfigModule.cs

@@ -0,0 +1,28 @@
+using Autofac;
+
+using Microsoft.Extensions.Configuration;
+
+namespace PluralKit.Core
+{
+    public class ConfigModule<T>: Module where T: new()
+    {
+        private readonly string _submodule;
+
+        public ConfigModule(string submodule = null)
+        {
+            _submodule = submodule;
+        }
+
+        protected override void Load(ContainerBuilder builder)
+        {
+            // We're assuming IConfiguration is already available somehow - it comes from various places (auto-injected in ASP, etc)
+
+            // Register the CoreConfig and where to find it
+            builder.Register(c => c.Resolve<IConfiguration>().GetSection("PluralKit").Get<CoreConfig>() ?? new CoreConfig()).SingleInstance();
+
+            // Register the submodule config (BotConfig, etc) if specified
+            if (_submodule != null)
+                builder.Register(c => c.Resolve<IConfiguration>().GetSection("PluralKit").GetSection(_submodule).Get<T>() ?? new T()).SingleInstance();
+        }
+    }
+}