Add a query "available_for_instant_withdrawal" to vault contract

[p-offtermatt]

Given an amount of shares, we want to predict whether a withdrawal for this amount of shares will be queued or not under the current contract conditions.

We can satisfy this usecase by adding a query that simply outputs the number that's available for instant withdrawal.

unverified typescript sketch for reference, need to double-check against withdraw function on vault contract:

  // 1. Vault queries                                                                                                             
  const availableForDeployment = await queryAvailableForDeployment();       // contract balance minus all queued
  const queueInfo = await queryWithdrawalQueueInfo();                       // for non_funded_withdrawal_amount                                                                                                                                                                                                                                                                         
  const { adapters } = await queryListAdapters();                           // [(name, AdapterInfo)]
                                                                                                                                                                                                                                                                                                                                                                                        
  // 2. Query each Automated adapter for withdrawable amount                                                                                                                                                                                                                                                                                                                          
  const adapterAvailable = await Promise.all(
    adapters
      .filter(([_, info]) => info.allocation_mode === "Automated")
      .map(([_, info]) => queryAdapterAvailableForWithdraw(info.address, vaultAddress, denom))
  );
  const totalFromAdapters = adapterAvailable.reduce((sum, amt) => sum + BigInt(amt), 0n);

  // 3. Mirror the contract's logic exactly
  const availableFromContract =
    BigInt(availableForDeployment) + BigInt(queueInfo.info.non_funded_withdrawal_amount);
  const totalAvailable = availableFromContract + totalFromAdapters;