Reorganize SDK source layout

src/BinaryLane.Api/Http/BinaryLaneHttpExecutor.cs

@@ -137,7 +137,7 @@ public sealed class BinaryLaneHttpExecutor : IBinaryLaneApiExecutor
         object? body = null,
         IReadOnlyDictionary<string, object?>? query = null,
         CancellationToken cancellationToken = default) =>
-        (await SendAsync<TResponse>(new BinaryLaneRequest(new HttpMethod("PATCH"), path) { Body = body, Query = query }, cancellationToken)
+        (await SendAsync<TResponse>(new BinaryLaneRequest(BinaryLaneHttpMethods.Patch, path) { Body = body, Query = query }, cancellationToken)
             .ConfigureAwait(false)).Body;
 
     /// <inheritdoc />

src/BinaryLane.Api/Http/BinaryLaneHttpMethods.cs

@@ -0,0 +1,9 @@
+using System.Net.Http;
+
+namespace BinaryLane.Api.V2.Http;
+
+/// <summary>HTTP methods required by the BinaryLane API beyond the framework's static set.</summary>
+internal static class BinaryLaneHttpMethods
+{
+    internal static readonly HttpMethod Patch = new("PATCH");
+}