Add wasm bindings for Pubkey and Keypair

sdk/tests/keypair.mjs

@@ -0,0 +1,14 @@
+import { expect } from "chai";
+import { init, Keypair } from "crate";
+init();
+
+describe("Keypair", function () {
+  it("works", () => {
+    const keypair = new Keypair();
+    let bytes = keypair.toBytes();
+    expect(bytes).to.have.length(64);
+
+    const recoveredKeypair = Keypair.fromBytes(bytes);
+    expect(keypair.pubkey().equals(recoveredKeypair.pubkey()));
+  });
+});