Initial commit, basic proxying working

Myriad/Rest/Exceptions/RatelimitException.cs

@@ -0,0 +1,29 @@
+using System;
+
+using Myriad.Rest.Ratelimit;
+
+namespace Myriad.Rest.Exceptions
+{
+    public class RatelimitException: Exception
+    {
+        public RatelimitException(string? message): base(message) { }
+    }
+
+    public class RatelimitBucketExhaustedException: RatelimitException
+    {
+        public RatelimitBucketExhaustedException(Bucket bucket, TimeSpan retryAfter): base(
+            "Rate limit bucket exhausted, request blocked")
+        {
+            Bucket = bucket;
+            RetryAfter = retryAfter;
+        }
+
+        public Bucket Bucket { get; }
+        public TimeSpan RetryAfter { get; }
+    }
+
+    public class GloballyRatelimitedException: RatelimitException
+    {
+        public GloballyRatelimitedException(): base("Global rate limit hit") { }
+    }
+}