Add initial configuration provider API

BepInEx.Core/Configuration/ConfigurationPath.cs

@@ -0,0 +1,17 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace BepInEx.Configuration
+{
+    public static class ConfigurationPath
+    {
+        public static readonly string KeyDelimiter = ":";
+
+        public static string Combine(IEnumerable<string> segements)
+        {
+            segements = segements ?? throw new ArgumentNullException(nameof(segements));
+            return string.Join(KeyDelimiter, segements.ToArray());
+        }
+    }
+}

BepInEx.Core/Configuration/ConfigurationProvider.cs

@@ -0,0 +1,13 @@
+using System.Collections.Generic;
+
+namespace BepInEx.Configuration
+{
+    public abstract class ConfigurationProvider
+    {
+        public IDictionary<string, string> RawData { get; }
+
+        public abstract void Load();
+
+        public abstract void Save();
+    }
+}