Correct consolidation amount display

[remyroy]

When presenting the information for a consolidation from one validator to another, we show all the balance going from the source to the target on the confirmation pop-up but that is wrong.

The protocol is defined here: https://github.com/ethereum/consensus-specs/blob/dev/specs%2Felectra%2Fbeacon-chain.md#new-process_pending_consolidations. It will move the minimum amount from the source validator between the effective balance and the actual balance. Your effective balance can be higher or lower than your actual balance depending on the current hysteresis zones (see https://www.attestant.io/posts/understanding-validator-effective-balance/). In the case where your effective balance is higher than your actual balance, your full actual balance will be moved to your target validator. In the most likely case where your effective balance is lower than your actual balance, only the effective amount will be moved to the the target validator and the remaining will be withdrawn to your original withdrawal address.

We should improve the way we display this information so that users are aware of where their money is going.

[remyroy]

This is especially concerning for users who want to consolidate from a type 1 validator with a good amount of balance above 32 ETH to a type 2 validator. Performing this consolidation will only send 32 ETH to the target validator and the remaining to the withdrawal address. It can causes issues for taxes purposes for instance.