embed plugin loader directly into the launcher

PluginLoader/Tools/PostHttpContent.cs

@@ -0,0 +1,25 @@
+using System.Net;
+
+namespace PluginLoader.Tools;
+
+public class PostHttpContent : HttpContent
+{
+    private readonly byte[] content;
+
+    public PostHttpContent(string content)
+    {
+        this.content = content == null ? null : Tools.Utf8.GetBytes(content);
+    }
+
+    protected override async Task SerializeToStreamAsync(Stream stream, TransportContext context)
+    {
+        if (content != null && content.Length > 0)
+            await stream.WriteAsync(content, 0, content.Length);
+    }
+
+    protected override bool TryComputeLength(out long length)
+    {
+        length = content.Length;
+        return true;
+    }
+}