Add getter to get staked balance

[webmaster128]

When you call StargateClient.getBalance/CosmWasmClient.getBalance, the response does not contain staked amounts. It would be good to have a simple method that does this.

An implementation I tested looks like this:

export function addCoins(lhs: Coin, rhs: Coin): Coin {
  if (lhs.denom !== rhs.denom) throw new Error("Trying to add two coins with different demoms");
  return {
    amount: Decimal.fromAtomics(lhs.amount, 0).plus(Decimal.fromAtomics(rhs.amount, 0)).atomics,
    denom: lhs.denom,
  };
}


  const { delegationResponses, pagination } = await queryClient.staking.delegatorDelegations(
    address,
  );
  assert(pagination?.nextKey?.length === 0); // TODO: support multiple pages
  const staked = delegationResponses.reduce((acc: Coin | null, resp) => {
    // console.log(resp.balance);
    assert(resp.balance);
    if (acc) {
      return addCoins(acc, resp.balance);
    } else {
      return resp.balance;
    }
  }, null);
  return staked;