feature: build overrides (#2212)

* add build overrides

* override docs

* add server submodule

* add overrides to build step

* remove testing api url

Co-Authored-By: Quahu <quahuu@gmail.com>

Co-authored-by: Quahu <quahuu@gmail.com>

experiment/Discord.Net.BuildOverrides/OverrideContext.cs

@@ -0,0 +1,30 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Discord.Overrides
+{
+    /// <summary>
+    ///     Represents context thats passed to an override in the initialization step.
+    /// </summary>
+    public sealed class OverrideContext
+    {
+        /// <summary>
+        ///     A callback used to log messages.
+        /// </summary>
+        public Action<string> Log { get; private set; }
+
+        /// <summary>
+        ///     The info about the override.
+        /// </summary>
+        public Override Info { get; private set; }
+
+        internal OverrideContext(Action<string> log, Override info)
+        {
+            Log = log;
+            Info = info;
+        }
+    }
+}