Function resolve_and_set_fee_token 

pub async fn resolve_and_set_fee_token<N>(
    provider: Option<&dyn Provider<N>>,
    chain: Option<Chain>,
    tx: &mut N::TransactionRequest,
    fee_payer: Option<Address>,
) -> Result<Option<Address>>
where
    N: Network,
    N::TransactionRequest: Default + FoundryTransactionBuilder<N>,

Resolves and applies the Tempo fee token selected by the network.

This must happen before computing a sponsor digest, because Tempo sponsor signatures commit to the fee token.