Don't show unconfirmed amount in the 'amount available' on the spend screen

[cygnet3]

We don't allow spending unconfirmed amounts, so we shouldn't show it either.

We can either remove it, or perhaps allow for spending unknown amounts. However, the latter could impose some risks that we may not want.

[Sosthene00]

I may have missed something, but since we don't detect utxos in mempool, we only add new spendable utxos by scanning blocks, hence if we add an amount to our balance it is necessarily a confirmed output, so we shouldn't have this issue, right?

[cygnet3]

We have this issue not for incoming (unconfirmed) transactions, but rather for the change outputs of outgoing unconfirmed transactions.

If a user has a 50k utxo and sends 10k, they receive a 40k change output. Even before confirming, we show this output already in the wallet balance, but users are not able to spend it yet.

It's pretty easy to just not include the unconfirmed change outputs in the spend screen. However we could also introduce the ability to allow users to spend unconfirmed change outputs, if we want.