message: refactor(core): use standard sign call in v2 AbstractUtxoCoin
  Previous code was needlessly elaborate
  Issue:
diff: @@ -1188,25 +1188,16 @@ export abstract class AbstractUtxoCoin extends BaseCoin {
  debug('Input details: %O', signatureContext);
  const sigHashType = utxolib.bitgo.getDefaultSigHash(self.network);
  + const redeemScript = signatureContext.unspent.redeemScript
  + ? Buffer.from(signatureContext.unspent.redeemScript, 'hex')
  + : undefined;
  + const witnessScript = signatureContext.unspent.witnessScript
  + ? Buffer.from(signatureContext.unspent.witnessScript, 'hex')
  + : undefined;
  + const scriptType = witnessScript ? (redeemScript ? 'p2shP2wsh' : 'p2wsh') : 'p2sh';
  + debug(`Signing ${scriptType} input`);
  try {
  - if (signatureContext.isP2wsh) {
  - debug('Signing p2wsh input');
  - const witnessScript = Buffer.from(signatureContext.unspent.witnessScript, 'hex');
  - const witnessScriptHash = utxolib.crypto.sha256(witnessScript);
  - const prevOutScript = utxolib.script.witnessScriptHash.output.encode(witnessScriptHash);
  - txb.sign(index, keyPair, prevOutScript, sigHashType, signatureContext.unspent.value, witnessScript);
  - } else {
  - const subscript = Buffer.from(signatureContext.unspent.redeemScript, 'hex');
  - const isP2shP2wsh = !!signatureContext.unspent.witnessScript;
  - if (isP2shP2wsh) {
  - debug('Signing p2shP2wsh input');
  - const witnessScript = Buffer.from(signatureContext.unspent.witnessScript, 'hex');
  - txb.sign(index, keyPair, subscript, sigHashType, signatureContext.unspent.value, witnessScript);
  - } else {
  - debug('Signing p2sh input');
  - txb.sign(index, keyPair, subscript, sigHashType, signatureContext.unspent.value);
  - }
  - }
  + txb.sign(index, keyPair, redeemScript, sigHashType, signatureContext.unspent.value, witnessScript);
  } catch (e) {
  debug('Failed to sign input:', e);
  signatureContext.error = e;
  