Remove crypto dependency

Summary:
Remove crypto dep, which was only used by NUX, to hash the elements that has been confirmed.

Sadly trickier than hoped; there is no uniform api in both browser and Node available that can take a sha-256 hash, and the browser APIs are async.

Reviewed By: aigoncharov

Differential Revision: D32721204

fbshipit-source-id: 32625f83bf6c60cedc4fb7096240c2fa0d8434a7

desktop/flipper-plugin/src/utils/sha256.tsx

@@ -0,0 +1,23 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+export function sha256(message: string): Promise<string> {
+  if (process.env.NODE_ENV === 'test') {
+    return Promise.resolve(message.substr(0, 100));
+  }
+  // From https://stackoverflow.com/a/48161723/1983583
+  const msgBuffer = new TextEncoder().encode(message);
+  return crypto.subtle.digest('SHA-256', msgBuffer).then((hashBuffer) => {
+    const hashArray = Array.from(new Uint8Array(hashBuffer));
+    const hashHex = hashArray
+      .map((b) => b.toString(16).padStart(2, '0'))
+      .join('');
+    return hashHex;
+  });
+}