message: refactor(core): deprecate hdPath in abstractUtxoCoin
  Sanitize the path construction.
  The previous derivation method ignored the `m/` prefix so don't
  explicitly add it.
  Issue:
diff: @@ -11,7 +11,6 @@ import * as debugLib from 'debug';
  import * as _ from 'lodash';
  import * as request from 'superagent';
  -import { hdPath } from '../../bitcoin';
  import { BitGo } from '../../bitgo';
  import * as config from '../../config';
  import * as errors from '../../errors';
  @@ -1064,9 +1063,9 @@ export abstract class AbstractUtxoCoin extends BaseCoin {
  derivationIndex = index;
  }
  - const path = 'm/0/0/' + derivationChain + '/' + derivationIndex;
  + const path = '0/0/' + derivationChain + '/' + derivationIndex;
  const hdNodes = keychains.map(({ pub }) => bitcoin.HDNode.fromBase58(pub));
  - const derivedKeys = hdNodes.map((hdNode) => hdPath(hdNode).deriveKey(path).getPublicKeyBuffer());
  + const derivedKeys = hdNodes.map((hdNode) => hdNode.derivePath(path).keyPair.getPublicKeyBuffer());
  const { outputScript, redeemScript, witnessScript, address } = this.createMultiSigAddress(
  addressType,
  @@ -1138,7 +1137,6 @@ export abstract class AbstractUtxoCoin extends BaseCoin {
  }
  debug(`Here is the public key of the xprv you used to sign: ${keychain.neutered().toBase58()}`);
  - const keychainHdPath = hdPath(keychain);
  const txb = bitcoin.TransactionBuilder.fromTransaction(transaction, self.network);
  self.prepareTransactionBuilder(txb);
  @@ -1147,7 +1145,7 @@ export abstract class AbstractUtxoCoin extends BaseCoin {
  return {
  inputIndex: index,
  unspent: currentUnspent,
  - path: 'm/0/0/' + currentUnspent.chain + '/' + currentUnspent.index,
  + path: '0/0/' + currentUnspent.chain + '/' + currentUnspent.index,
  isP2wsh: !currentUnspent.redeemScript,
  isBitGoTaintedUnspent: self.isBitGoTaintedUnspent(currentUnspent),
  error: undefined as Error | undefined,
  @@ -1167,7 +1165,7 @@ export abstract class AbstractUtxoCoin extends BaseCoin {
  );
  continue;
  }
  - const privKey = keychainHdPath.deriveKey(signatureContext.path);
  + const privKey = keychain.derivePath(signatureContext.path).keyPair;
  privKey.network = self.network;
  debug('Input details: %O', signatureContext);
  