Updating unity assets (#82)

UnityAssets/Bls.jslib

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+var BLS = {
+  VerifySignature: function (publicKey, messageHash, signature) {
+    return blsVerify(publicKey, messageHash, signature);
+  },
+};
+mergeInto(LibraryManager.library, BLS);

UnityAssets/README

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+The following files should be added to the `Plugins/ICP.NET/` directory in Unity
+- UnityHttp.cs - An alternative HttpClient that uses UnityWebRequest (needed for WebGL)
+	To use, create a `UnityHttpClient` instance and when creating an `HttpAgent` pass it as a parameter instead of the default
+- WebGlBlsCrytography.cs - The WebGL version of the bls signature verify library, run in the browswer vs in C#/WASM
+	To use, create a `WebGlBlsCrytography` instance and when creating an `HttpAgent` pass it as a parameter instead of the default
+- Bls.jslib - The bridge between the C# code and JS to allow C# to invoke the JS bls signature verification
+
+Other files:
+- bls.js - Add to unity project and reference from an HTML file with a script tag. Loads in the JS bls signature verification that will be used with `WebGlBlsCrytography.cs`.
+	To generate the bls.js file, run `npx esbuild --bundle src/index.ts --outfile=dist/index.js` on github.com/dfinity/agent-js project in the directory `packages/bls-verify/`
+	Also modify the bls.js file to change `var blsVerify = ...` to `window.blsVerify = ...`. // TODO find a better way to export function

UnityAssets/WebGlBlsCryptography.cs

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+using Cysharp.Threading.Tasks;
+using EdjCase.ICP.Agent.Agents.Http;
+using EdjCase.ICP.BLS;
+using System;
+using System.Net;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using System.Threading;
+using System.Threading.Tasks;
+using UnityEngine;
+using UnityEngine.Networking;
+
+#if UNITY_WEBGL
+public class WebGlBlsCryptography : IBlsCryptography
+{
+    public bool VerifySignature(byte[] publicKey, byte[] messageHash, byte[] signature)
+    {
+        return BrowserBlsLib.VerifySignature(publicKey, messageHash, signature);
+    }
+}
+
+internal static class BrowserBlsLib
+{
+    [DllImport("__Internal")]
+    public static extern bool VerifySignature(byte[] publicKey, byte[] messageHash, byte[] signature);
+}
+#endif
+