message: refactor(core): use secp256k1 for token ECDH
  This method is not as reliant on `ECPair` internals and works with the
  `bip32` library.
  The method is tested here:
  Issue:
diff: @@ -1049,9 +1049,13 @@ export class BitGo {
  const clientDerivedNode = hdPath(clientHDNode).derive(derivationPath);
  const serverDerivedNode = hdPath(serverHDNode).derive(derivationPath);
  - // calculating one-time ECDH key
  - const secretPoint = serverDerivedNode.keyPair.__Q.multiply(clientDerivedNode.keyPair.d);
  - const secret = secretPoint.getEncoded().toString('hex');
  + const publicKey = serverDerivedNode.keyPair.getPublicKeyBuffer();
  + const secretKey = clientDerivedNode.keyPair.d.toBuffer(32);
  + const secret = Buffer.from(
  + // FIXME(BG-34386): we should use `secp256k1.ecdh()` in the future
  + // see discussion here https://github.com/bitcoin-core/secp256k1/issues/352
  + secp256k1.publicKeyTweakMul(publicKey, secretKey)
  + ).toString('hex');
  // decrypt token with symmetric ECDH key
  let response: TokenIssuance;
  