Show available amounts for staking messages

[ryanchristo]

When creating a staking message proposal, we currently only show the amount the group policy has available to delegate, which is based on the group policy's account balance, but the amount available for redelegate, undelegate, and claim are different amounts and will require additional queries if we want to provide a "max" option and available preview.

We are currently passing an empty array to the balances field of the AmountField component for staking messages.

balances={[]} // TODO: use amount staked on validator