Add IHttpContentSerializer and GraphHttpContentSerializer

(cherry picked from commit b6f7553)

ShopifySharp/Infrastructure/Serialization/Http/GraphHttpContentSerializer.cs

@@ -0,0 +1,38 @@
+#if NETSTANDARD2_0
+using System.Text;
+#else
+using System.Buffers;
+using System.Net.Http.Headers;
+#endif
+using System.Collections.Generic;
+using System.Net.Http;
+using System.Text.Json;
+
+namespace ShopifySharp.Infrastructure.Serialization.Http;
+
+public class GraphHttpContentSerializer(JsonSerializerOptions jsonSerializerOptions) : IHttpContentSerializer
+{
+    public HttpContent SerializeGraphRequest(RequestUri requestUri, GraphRequest graphRequest)
+    {
+        var jsonData = new Dictionary<string, object>
+        {
+            { "query", graphRequest.Query },
+            { "variables", graphRequest.Variables },
+        };
+
+#if NET6_0_OR_GREATER
+        var bufferWriter = new ArrayBufferWriter<byte>();
+        using var utf8JsonWriter = new Utf8JsonWriter(bufferWriter);
+
+        JsonSerializer.Serialize(utf8JsonWriter, jsonData, jsonSerializerOptions);
+
+        var content = new ReadOnlyMemoryContent(bufferWriter.WrittenMemory);
+        content.Headers.ContentType = new MediaTypeHeaderValue("application/json");
+#else
+        var jsonStr = JsonSerializer.Serialize(jsonData, jsonSerializerOptions);
+        const string mediaType = "application/json";
+        var content = new StringContent(jsonStr, Encoding.UTF8, mediaType);
+#endif
+        return content;
+    }
+}

ShopifySharp/Infrastructure/Serialization/Http/IHttpContentSerializer.cs

@@ -0,0 +1,8 @@
+using System.Net.Http;
+
+namespace ShopifySharp.Infrastructure.Serialization.Http;
+
+public interface IHttpContentSerializer
+{
+    public HttpContent SerializeGraphRequest(RequestUri requestUri, GraphRequest graphRequest);
+}