TxBuilder: Add an option to only use confirmed utxo's

[ErikDeSmedt]

Describe the enhancement

I want to create a transaction and ensure that prevovut has been confirmed onchain.

Similar to ChangeSpendPolicy I'd like to introduce a ConfirmationSpendPolicy.
This could be used to spend only Confirmed, Trusted or Any output.

The code to use it could look like the example below

wallet.create_tx()
    .add_recipient(address.script_pubkey(), payment_amount)
    .only_spend_confirmed_utxos()
    .finalize()

Use case

When creating a transaction I want to ensure it cannot be doublespent.
If I use an unconfirmed and untrusted prevout, I cannot guarantee the transaction will not be doublespent

Additional context