Add HTTP(S) proxy (#208)

Source/GrasscutterTools/Eavesdrop/Internals/NativeMethods.cs

@@ -0,0 +1,12 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Eavesdrop
+{
+    internal static class NativeMethods
+    {
+        [DllImport("wininet.dll", SetLastError = true, CharSet = CharSet.Auto)]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        public static extern bool InternetSetOption(IntPtr hInternet, int dwOption, IntPtr lpBuffer, int dwBufferLength);
+    }
+}